DEPARTMENT OF EMBRYOLOGY. 109 



cavity, and the path by which absorbed substances leave the omentum 

 is not a lymphatic but a hsemic one. 



Dr. E. V. Cowdry has studied the so-called ''chromophile cells," 

 especially their canalicular apparatus and their mitochondria, in the 

 brain of the white mouse. He has found that chromophilic cells occur 

 under normal conditions in the brain of the white mouse and are dis- 

 tributed unequally in the different parts of the nervous system. They 

 are most abundant in the cerebral cortex, and are progressively less 

 numerous in the cerebellum, corpus striatum, thalamus, midbrain, and 

 medulla. They are of very rare occurrence in the spinal cord, spinal 

 ganglia, and sensory ganglia of the cranial nerves. Chromophilic 

 cells, as seen in fixed and stained preparations, vary greatly in struc- 

 ture. There is usually more or less shrinkage of the cell-body and the 

 nucleus may also be shrunken. The acidophilic and basophilic nuclei 

 are particularly prominent, and the ground-substance of the nucleus 

 stains intensely with both acid and basic dyes. There is an increase 

 in the amount of Nissl substance, the Nissl bodies becoming confluent 

 and foiToing a homogeneous mass. The cell is hyperchromatic and 

 the canalicular apparatus is unaltered. The mitochondria either 

 increase in number or stain intensely, or else lose their discrete outlines 

 and form a homogeneous diffuse deposit which stains intensely by the 

 mitochondrial methods of technique. This change in the mitochondria 

 occurs in the cell-process in the neighborhood of the cell as well as in 

 the cell-body. Although the nucleus may be completely obscured by 

 this cloud of mitochondrial substance, it still remains and stains in the 

 usual way with hematoxylin and eosin. The labihty of the mito- 

 chondria and the constancy of the canalicular apparatus in the chro- 

 mophilic cells confimi the author's view that these two structures are 

 physiologically as well as morphologically distinct. 



The same author has summarized in a general article our knowledge 

 of the general functional significance of the mitochondria. He reviews 

 in succession the data concerning their morphology, their relation to 

 other cytoplasmic constituents, to metabolism, to histogenesis, to 

 inheritance, and to the pathology of the cells; and gives for the first 

 time an account of their chemical properties, including their behavior 

 towards vital stains, of which he has made a special study. His con- 

 clusions are that a great deal of work still remains to be done before 

 we can hope to understand the functional significance of these bodies. 



HUMAN EMBRYOLOGY IN GENERAL. 



Owing to our increasing efforts, the collection of human embryos has 

 continued to grow rapidly. Twenty-five years ago it took 10 years to 

 collect our first 100 specimens; 5 years to collect the second hundred; 

 3 years for the third hundred ; 2 years for the fourth hundred. And 

 now, since the collection has been taken over by the Carnegie Institu- 



