288 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the hfemal and lymphatic systems. The view opposed to the augioblasfe 

 theory is that of local origin. According to this view, mesenchyme 

 may, in practically any region of the body, transform into vascular 

 tissue. 



Reagan's results furnish evidence in favour of the following proposi- 

 tions : — 1. That mesenchyme in many regions of the body can turn, 

 into endothelium, and that endothelium is not an ingrowth from vessels 

 on the yolk. 2. That prevascular tissue can come from more than one 

 germ -layer. 3. That mesenchyme cells which can form a given type 

 of blood-cell are not confined to a narrowly limited region of the 

 embryo. 4. That endothelium can transform into blood-cells. 



Internal Secretion.* — J. F. Gudernatsch, continuing his studies on 

 internal secretion, describes a set of experiments undertaken to study the 

 influence on the development of tadpoles of several distinct constituents 

 of the thyroid and thymus. By a detailed chemical procedure each, 

 organ was split into seven products, all in aqueous solutions. The 

 nitrogen content of the various solutions was determined, and the same 

 concentration used for each set of tadpoles. The constituents are 

 arranged in a series showing their influence on differentiation and on 

 growth. In general the serial arrangement of tlie thymns products is 

 almost the opposite of the thyroid series, but it was not found that the 

 corresponding constituents of the two glands were most active in counter- 

 acting each other. Older animals react more rapidly to the thyroid 

 treatment than younger animals. The thyroid as a whole, and some of 

 its constituents, proved the most powerful stimulus to differentiation,, 

 while growth was suppressed almost entirely. Only two of the thymus 

 products delayed differentiation to any considerable extent. A complete 

 set of growth curves is not given. 



b. Histology. 



Golgi Apparatus in Cells.f — Alwin M. Pappenheimer has studied 

 a great variety of cells and finds the Golgi apparatus everywhere. It is a 

 cytoplasmic structure of considerable complexity and size, demonstrable 

 by prolonged fixation in osmic acid, or by silver impregnation and reduc- 

 tion. It includes a lipoid component. It is invisible in the living cell. 

 Whether it is canalicular or filamentous remains uncertain. The con- 

 stant topography and the relation to the cytocentrum would favour the 

 idea of solid or semi-solid consistence. 



Sensory Elements in Human Hypophysis.|— W. Sohier Bryant 

 has found sensory elements in maculae on the posterior wall of the 

 pituitary cavity, and sometimes, apparently, on the anterior wall. The 

 maculaB are composed of tall columnar ciliated sensory cells interspersed 

 with bipolar cells, which have their nuclei towards the periphery ; 



* Anat. Kecord, ii. (1917) pp. 357-9. 



+ Anat. Record, li. (1916) pp. 107-48 (22 figs.)." 



; Anat. Record, xi. (1916) pp. 25-7 (1 fig.). 



