THE PROTOPLASMIC SYSTEM 



my observations I venture the opinion that chromidia and 

 mitochondria represent stages in the transformation of 

 granules of nuclear origin. 



Of granules other than mitochondria and chromidia 

 found in eggs, pigment is most striking. Many eggs seen 

 en masse have beautiful colors — various shades of red, 

 orange, yellow or green. There are some species which 

 have eggs of two distinct hues; thus individuals of the 

 little marine worm, Autolytus varians, have either red or 

 green eggs. The pigment of sea-urchin eggs has been 

 shown to be a lipochrome. 



Occasionally crystals can be demonstrated in eggs. Thus 

 Aleves has described fine slender bodies found in fertilized 

 eggs of Psanvmechuius and I have found them also in ferti- 

 lized eggs of Echinarachnius. That such formations are 

 increased in cross-fertilized eggs^ I do not doubt, but that 

 they are solely due to the effect of the foreign sperma- 

 tozoon is to be questioned in view of Meves' and my own 

 observations. 



Some of these cytoplasmic inclusions, as well as others, 

 that are not here discussed as, for example, secretion- 

 granules which leave the cell, are certainly temporary 

 structures. Study of the history of the egg from its 

 earliest formation, when Its cytoplasm always appears 

 homogeneous, through the stages during which it becomes 

 laden with Inclusions, teaches that Inclusions appear in the 

 cytoplasm during development. The building up of cyto- 

 plasmic Inclusions Is an indication that the egg takes in 

 food-material from Its surrounding medium. Indeed, in 

 some eggs, as those of the flatworms, the yolk, elaborated 

 by special gland-cells, Is merely deposited around the egg. 



In limiting the application of the term, cytoplasm, to 

 the clear and almost homogeneous menstruum or ground- 



^ Tennent, IQ20; Hibbard, ig22. 



57 



