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mals. The rudiments of the eye are present. The reciprocal of this cross 

 was not attempted. 



In this cross many of the eggs stop their development at the closure of 

 the blastophore with the main axis of the embryo laid down. Many of the 

 eggs continue their development to a varying degree and with varying nor- 

 mality. None of them, however, are developed in a perfectly normal man- 

 ner. Among these embryos which live for a week or ten days, the most 

 grotesque features appear. The yolk and embryo become pigmented, often 

 very heavily, though not normally. On the yolk the pigment cells may be 

 quite large, or quite finely branched, and they are likely to congregate in 

 certain places, instead of having a distribution such as is found on the 

 normal embryo. A favorite place for such congregation is on the surface 

 between the very large pericardial cavity and the yolk where the pigment 

 cells may densely cover the area. In the embryo the distribution of the pig- 

 ment may be more or less regular. Thus along the dorsal side two rows 

 may appear in the anterior portion, one on either side, these converging into 

 a single median band running well out towards the posterior end. Both 

 kinds of pigment cells, red and black, are well represented. 



The heart is always developed in these embryos and usually pulsates 

 quite vigorously. The excessive development of the pericardial cavity which 

 usually appears as a large clear vesicle — sometimes one-third the size of 

 the yolk — has the effect of stretching the heart out to a great length. As a 

 consequence a curious series of modifications obtain in the different embryos, 

 from a relatively normal heart, although always more or less elongated, to 

 strikingly aberrant conditions, in which the pulsating portion of the heart 

 has become' associated with the yolk bordering on the lower portion of the 

 large pericardial cavity, and is a mere mass of cells without apparent 

 structuix-, and connected with the upper border of the pericardial cavity 

 near the embryo, by an extremely slender protoplasmic thread. No lumen 

 can be detected in either portion and the only effect of the rythmical and 

 vigorous pulsations of the lower yolk portion is to stretch this filament, and 

 pull the yolk upwards so that the latter rocks continually. The usual thing 

 is for the heart to develop a cavity in the interior and the peristaltic pulsa- 

 tions pass in the right direction, i. e., toward the embryo. Out of hundreds 

 of such hearts, many of them relatively normal, which I have examined, 

 I have never seen one carrying blood, certainly not blood containing red 

 corpuscles. In regard to the rest of the circulatory system there is very 



