195 



Summary of the normally placed germ-cells in 5 monsters 



of Raj a batis. 



Raja batis no. 747 is the equivalent of a 6 mm embryo. The 

 embryo was frightfully contorted, and the majority of the sections cut 

 t in three ditferent places. The embryo is apparently normal up to 

 and including the auditory thickening. There are no obvious gill- 

 pouches. In front of the auditory neuroepithelium the gut is abnormal, 

 and forms double sacs. There appear to be no traces of primary optic 

 vesicles. 



There are very few germ-cells at all of the normal size, and pos- 

 sibly of these two or three may be normally placed. The majority of 

 the germ-cells are represented by megaspheres. These form a great 

 heap upon, i. e., within, the blastoderm just beneath the embryo, and 

 others of them are within it in various places. Thus, they are seen 

 in the nervous system, under the epiblast, in the mesoderm (whether 

 any or many of these megaspheres are "normally placed" cannot be 

 readily determined owing to the obliquity of the sections), in the hypo- 

 blast, in the head (a few), and, lastly, there are many in the germinal 

 path between splanchnopleure and gut. Some few of the megaspheres 

 lie in the blastoderm behind the embryo. 



In the present writing the results of the study of these monsters 

 may be allowed to speak for themselves. All that the writer would 

 do would be to direct attention to the light thrown by them 1) upon 

 the megaspheres, and 2) upon the question of the origin, the number, 

 and the migrations of the germ-cells of Raja. 



If the extra-embryonic origin of the germ-cells of Raja and their 

 migratory movements be still doubtful, it would be of interest to learn 

 what interpretation should be put upon the facts, observed in the 

 monsters. 



To these there will fall to be added the observations, still to be 

 made and recorded, upon the two pairs of like-twins. Whatever the 

 nature of these may turn out to be, it is hardly likely, that they can 

 be of a more suggestive or significant character than those above re- 

 corded. 



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