420 E. I. WERBER 



body of the embryo is observed also externally to be partly 

 duplicated (figs. 21 and 22). The musculature is not doubled; 

 yet there is a decided increase of it in bulk. The alimentary 

 tract is also single and even incomplete, some of its parts lack- 

 ing altogether. In sections through about the posterior fourth 

 of the embryo there appear just about the level where the in- 

 testine ends, two large cavities lined with endothelium whose gen- 

 esis and morphological significance I am unable to interpret. 



The genesis of the chief morphological deviations of this 

 embryo might be imagined in the following manner: 



The part of the embryo which was to form the head has sus- 

 tained the greatest destructive alterations from the sojourn in 

 the toxic solution. Hence the extreme malformation and the 

 defects of this part of the body. The bilateral parts of the germ- 

 ring have apparently — owing to osmotic pressure — failed at 

 first to fuse completely, this fusion occurring only later when 

 some anlagen have, in this way, been doubled. The increase 

 in osmotic pressure has also most likely contributed to the frag- 

 mentation and dispersion of some anlagen, as is evidenced by 

 the condition of the notochord and the spinal cord. 16 



While the embryo is not a double monster in the strict sense 

 of the word, it well illustrates the manner in which — according 

 to Fischel' s suggestion — certain double embryos may arise 

 during the formation of the embryonic body. It would also 

 seem to offer strong support to our contention that the same 



Fig. 5 From acetone solution (35 cc. gram-molecular to 50 cc. of sea-water), 

 14 days old. 



Fig. 6 (a and b) From acetone solution (35 cc. gram-molecular to 50 cc. of 

 sea-water), 16 days old; i.e., 'isolated eye.' 



Fig. 7 From acetone solution (35 cc. gram-molecular to 50 cc. of sea-water), 

 14 days old. 



Fig. 8 From acetone solution (35 cc. gram-molecular to 50cc.of sea-water), 

 14 days old, pc, pericardial vesicle. 



Fig. 9 From acetone solution (35 cc. gram-molecular to 50 cc. of sea-water), 

 one of the 'twins' amorphous, 14 days old, pc, pericardial vesicle. 



16 Neither verbal description nor the accompanying figures (of necessity 

 limited in number) are adequate to give a complete picture of these conditions. 

 To obtain an adequate idea of them and the dissociation that underlies them and 

 is apparent in the sections, it is necessary to examine the latter in the series. 



