632 JOHN BEARD^ 



never a small one. In No. 454 it is not far short of being one in 

 every three of the total. In another embryo (No. 657, 21.5 mm), in 

 which the germ-cells of rather more than one hundred sections were 

 counted, nearly 50 7o were abnormally placed. In B. batis 627 

 (28.25 mm) the figures can be given in greater detail. Here again 

 no attempt has yet been made to estimate the total of the germ-cells, 

 but only those in a number of consecutive rows of sections have been 

 counted. 



Table 2. Raja hatis No. 6 2 7, slide 4. 

 Row 1 in 33 sections 1 abnormally placed 2 normally 



In 7 rows containing 242 sections there are 47 abnormally placed 

 and 122 normally placed germ-cells. That is to say, among 169 germ- 

 cells there are nearly 28 ^/o in abnormal situations! 



At a later stage very similar figures will be given for embryo 

 No. 448. These embryos have not been chosen for description, because 

 of any high percentage of abnormality, such as this. Their germ- 

 cells were wholly or partly tabulated, because the embryos were per- 

 fect specimens, with germ-cells so sharply defined by the staining, that 

 an enumeration of them was comparatively an easy, or, at any rate, 

 not too difficult a task. 



In fine, in all my embryos of less than 45 mm, and more than, 

 say, 6 mm, preserved in various years from 1889 to 1899, it is not 

 an exaggeration to say, that not a single one of them has the whole 

 of its germ-cells anywhere near the "germinal ridges". The number 

 of such embryos, of which I possess complete series of sections of 

 the trunk, is not less, probably more, than two hundred. 



It is, of course, out of question, to describe, or even to examine 

 carefully, all of these embryos within an even moderately long period. 

 Only typical cases can be taken; and, that even the above three are 

 such, at any rate for the sizes dealt with, may be gathered from the 

 circumstance, that in any one of them all, or practically all, the "ab- 

 normalities", found in the others, or in any one of more than thirty 

 others, may be seen. 



