We think that the trial court erred in not granting the caveatee's motion for a directed verdict. The rule of our cases is that urged on us by the caveatee: that while testimony tending to establish competency may relate to periods preceding or succeeding the execution of the will, testimony tending to establish incompetency must reasonably relate to the date of execution, Jackson v. Jackson, 249 Md. 170, 173-75, 238 A.2d 852 (1968); Arbogast v. MacMillan, supra, 221 Md. at 525-26; Masius v. Wilson, 213 Md. 259, 268, 131 A.2d 484 (1957); Willis v. Willis, 171 Md. 144, 152, 188 A. 217 (1936); Daugherty v. Robinson, 143 Md. 259, 268, 122 A. 124 (1923); Hutchins v. Hutchins, 135 Md. 401, 404, 109 A. 121 (1919); Kelly v. Kelly, 103 Md. 548, 553, 63 A. 1082 (1906); Baugher v. Gesell, 103 Md. 450, 457, 63 A. 1078 (1906); Gesell v. Baugher, 100 Md. 677, 682, 60 A. 481 (1905). If that were not so, a caveat action could never be defended, as it frequently is, on the ground that a will was executed at a time when the testator had a lucid interval. While there was testimony to support the notion that Julia was eccentric, erratic, forgetful, and may have had delusions of persecution, this, standing alone, is not enough.

However, a reading of the cases reveals that a challenge to the framed issues was not actually involved and that they were decided on evidentiary matters. See Giardina v. Wannen, 228 Md. 116, 179 A.2d 357 (1962); Daugherty v. Robinson, 143 Md. 259, 122 A. 124 (1923); Davis v. Denny, 94 Md. 390, 50 A. 1037 (1902). Also there are cases which, by way of dicta, set forth various factors involving the actions and knowledge of the testator regarding his affairs which may be considered in determining mental competency, and his knowledge as to the contents of the will, as illustrated by Baker v. Baltimore Trust Company, 154 Md. 390, 392, 140 A. 599 (1928) and Taylor v. Creswell, 45 Md. 422, 430, 431 (1876), but we do not look upon these cases as authority for the requirement of separate issues on each of these evidentiary matters.

See also Masius v. Wilson, 213 Md. 259, 131 A.2d 484 (1957) [evidence tending to show incapacity must relate to the critical date]. And see Daugherty v. Robinson, 143 Md. 259, 122 A. 124 (1923) [evidence of incapacity is not admissible except as of date of will]. So, without taking into consideration the positive testimony of the attesting witnesses and the scrivener, all of whom were attorneys-at-law, that the testator was possessed of a sound mind, and the testimony of his friends and neighbors, we think it is clear that the testimony of the urologist was not sufficient to support a rational inference of mental incapacity at the time the will was executed, and for that reason, the trial court should have directed a verdict for the caveatee or entered a judgment n.o.v. on the issue of mental capacity.

And, although it was within the power of the caveator to ascertain how far the subscribing witness had satisfied herself of the competency of the testatrix [ Jones v. Collins, supra], the caveator neglected to do so. It has been held that a witness, who has not been asked on direct examination nor had given his opinion of the mental capacity of the testatrix, but testified merely to the factum of the will, could not be cross-examined as to mental capacity at that time. Daugherty v. Robinson, 143 Md. 259, 265, 122 A. 124 (1923). But, there was no reason why the caveator should not have examined the subscribing witness at a later stage of the proceedings had she desired.

But, in either instance, if such testimony stands alone and there is no evidence tending to show that such incapacity before the date of the will continued to the date of its execution, it is legally insufficient to establish incompetency at the date of the execution of the will." Among the other Maryland cases which have so held in an unbroken line are Townshend v. Townshend, 7 Gill 10 at page 27; Dorsey v. Warfield, 7 Md. 65 at page 73; Weems v. Weems, 19 Md. 334 at page 345; Waters v. Waters, 35 Md. 531 at page 542; Williams v. Lee, 47 Md. 321 at page 326; The Berry Will Case, 93 Md. 560 at pages 579 and 580, 49 A. 401; Struth v. Decker, 100 Md. 368 at pages 378, 379, 59 A. 727; Grill v. O'Dell, 113 Md. 625 at page 635, 77 A. 984; Harris v. Hipsley, 122 Md. 418 at page 432, 89 A. 852; Smith v. Shuppner, 125 Md. 409 at page 417, 93 A. 514; Daugherty v. Robinson, 143 Md. 259 at page 266, 122 A. 124; Cronin v. Kimble, 156 Md. 489, page 496, 144 A. 698; Smith v. Biggs, 171 Md. 528 at page 535, 189 A. 256; Acker v. Acker, 172 Md. 477 at page 487, 192 A. 327. The contention of the appellants is that no sufficient facts are stated by the three lay witnesses who testified to the testator's incapacity to justify the admission in evidence of their opinions.

The practice of permitting an expert to express an opinion based upon facts in the evidence which he has heard or read, upon the assumption that those facts are true, is well established in this state. Jerry v. Townshend, 9 Md. 145; Baltimore City Pass. Ry. Co. v. Tanner, 90 Md. 315, 45 A. 188; Berry Will Case, 93 Md. 560, 49 A. 401; Owings v. Dayhoff, 159 Md. 403, 151 A. 240; Rickards v. State, 129 Md. 184, 98 A. 525; Daugherty v. Robinson, 143 Md. 259, 122 A. 124; Gordon v. Opalecky, 152 Md. 536, 137 A. 299; Balto. O.R. Co. v. Brooks, 158 Md. 149, 148 A. 276; Baltimore v. State, 132 Md. 113, 103 A. 426; Quimby v. Greenhawk, 166 Md. 335, 337, 171 A. 59; Mt. Royal Cab Co. v. Dolan, 168 Md. 633, 179 A. 54; Calder v. Levi, 168 Md. 260, 177 A. 392; Mead v. Gilbert, 170 Md. 592, 185 A. 668.

To the same effect, in the case of Quimby v. Greenhawk, 166 Md. 335, 171 A. 59, 61, Judge Parke observed that: "It has been the practice in this jurisdiction for some years to permit an expert to express his opinion upon facts in the evidence which he has heard or read, upon the assumption that these facts are true." See Jerry, a Negro v. Townshend, 9 Md. 145; Baltimore City Pass. Ry. Co. v. Tanner, 90 Md. 315, 45 A. 188; Berry Will Case, 93 Md. 560, 49 A. 401; Owings v. Dayhoff, 159 Md. 403, 151 A. 240; Baltimore City v. State, 122 Md. 113, 103 A. 426; Rickards v. State, 129 Md. 184, 98 A. 525; Daugherty v. Robinson, 143 Md. 259, 122 A. 124; Gordon v. Opalecky, 152 Md. 536, 137 A. 299; Balto. O.R. Co. v. Brooks, 158 Md. 149, 148 A. 276. In other words, while it is clear that an expert witness may be asked an opinion upon a state of facts, hypothetically put, it is equally clear that the facts submitted must be based upon evidence, and if no evidence has been adduced to support the hypothesis of the question, an objection to it should be sustained.

Under these circumstances, an expression of a contrary opinion has for its foundation no rational basis. Berry Will Case, 93 Md. 560, 578, 49 A. 401; Scheller v. Schindel, 153 Md. 547, 138 A. 415; Daugherty v. Robinson, 143 Md. 259, 122 A. 124. Exceptions 17 to 22 relate to rulings made with respect to the testimony of another lay witness, Madeline C. Acker, committee of Joel Acker. She was permitted to contrast his appearance prior to the stroke with that after 1928. Witness saw testator twice in June, 1934, and he made no effort to converse with her, and refused to answer her questions, but as this court observed in Smith v. Biggs, supra, a person may choose not to talk.

Eight of the exceptions arising on objections to testimony relate to the form of hypothetical questions submitted to medical experts, and it will be convenient to consider these first. It has been the practice in this jurisdiction for some years to permit an expert to express his opinion upon facts in the evidence which he has heard or read, upon the assumption that these facts are true. Jerry v. Townshend (1856), 9 Md. 145, 159; Baltimore City Pass. Rwy. Co. v. Tanner, 90 Md. 315, 45 A. 188; Berry Will Case, 93 Md. 560, 579, 49 A. 401; Owings v. Dayhoff, 150 Md. 403, 151 A. 240; Rickards v. State, 129 Md. 184, 190, 98 A. 525; Daugherty v. Robinson, 143 Md. 259, 122 A. 124; Gordon v. Opalecky, 152 Md. 536, 137 A. 299; Balto. O.R. Co. v. Brooks, 158 Md. 149, 148 A. 276; Baltimore v. State, 122 Md. 113, 103 A. 426. In other words, while the better practice is to incorporate in a hypothetical question all the facts on which an expert witness is asked to give an opinion, yet the hearing or reading of the testimony is accepted as an imperfect substitute for the formal hypothetical question in furnishing the data for inference by the expert witness.

The weight of the evidence may be considered on a motion for a new trial, but not on a prayer demurring to the evidence as legally insufficient. These principles have been firmly established in Maryland by a long and uniform course of judicial decisions in numerous cases, including Weitzel v. List, 161 Md. 28, 155 A. ___; Friedman v. Hendler Creamery Co., 158 Md. 131, 148 A. 426; Purdum v. Edwards, 155 Md. 178, 141 A. 550; General Automobile Owners' Assn. v. State, use of Penn, 154 Md. 204, 140 A. 48; Abuc Trading Corp. v. Jennings, 151 Md. 392, 135 A. 166; Clough Molloy v. Shilling, 149 Md. 189, 131 A. 343; Taxicab Co. v. Hamburger, 146 Md. 122, 125 A. 914; Kelly v. Huber Baking Co., 145 Md. 321, 125 A. 782; Daugherty v. Robinson, 143 Md. 239, 122 A. 124; Capitol Traction Co. v. McKeon, 132 Md. 70, 103 A. 314; Moyer v. Justis, 112 Md. 220, 76 A. 496; Mallette v. British-American Assur. Co., 91 Md. 471, 46 A. 1005; Western Md. R. Co. v. Kehoe, 86 Md. 43, 37 A. 799; Jones v. Jones, 45 Md. 144. The appellee has cited cases in which testimony of a party or witness as to the result of an alleged observation has been treated as devoid of probative value because it was in conflict with unquestionable facts. For example, in cases of crossing accidents, the statement of the plaintiff that he looked for, but did not see, an approaching train or vehicle, which he must have seen if he had actually looked, has been held to be unworthy of belief.