654 SUMMARY OF CURRENT RESEARCHES RELATING TO 



earliest and latest stages of the uterine egg, the treatment of the inter- 

 mediate condition, represented by the cellular wall of a blastodermic 

 vesicle with fluid contents, is difficult. In the earlier years of their 

 research the material was lived with picro-sulphuric or picro-nitric fluids ; 

 latterly, the authors have generally used picro-corrosive-acetic solution. 

 They regard double imbedding in cedar-oil celloidin and paraffin as 

 indispensable for embryological work of a critical character. The sec- 

 tions, after having been stuck on the slides with Mayer's albumen and 

 thoroughly dried, were coated with a thin solution (0* 5-0* 75 p.c.) of 

 celloidin to insure perfect adhesion. When the celloidin has set, the 

 slides are placed in a mixture of 90 p.c. alcohol, to which 10 p.c. of 

 chloroform has been added, and this chloroform-alcohol must be used 

 whenever alcohol is required. The sections were stained as a rule with 

 hamiatoxylin or hamiatein, and couuterstained with eosin. In surface 

 observation great advantage was derived from the use of the binocular 

 stereoscopic Microscope. The paper is illustrated by numerous photo- 

 micrographs and some drawings. 



Studying the Structure of (Edogonium.* — C. van Wisselingh 

 fixed and hardened the material in Flemming's fluid, and afterwards 

 macerated it in 20 p.c. chromic acid. After the chromic acid had been 

 thoroughly washed out, the preparations were stained with brilliant blue 

 extra. 



Demonstrating the Spermatogenesis of Hornets.f — F. Meves and 

 J. Duesberg fixed the material in Hermann's and Flemming's mixtures 

 (1 p.c. platinum chloride or 1 p.c. chromic acid 15 c.cm., 2 p.c. osmic 

 acid 2 c.cm., glacial acetic acid (1 c.cm.), which were diluted with an 

 equal quantity of distilled water. 



The sections were stained with iron-hamiatoxylin. 



For demonstrating mitochondria some of the testicles were fixed in 

 the following modification of Flemming's fluid (1 p.c. chromic acid 

 15 c.cm., 2 p.c. osmic acid 4 c.cm., glacial acetic acid 3 drops) ; and 

 further treated by Benda's method thus : — 1 . After an hour's washing 

 the material was placed for 24 hours in a mixture of equal parts 

 acet. pyrolig. rectif. and 1 p.c. chromic acid. 2. For 24 hours 2 p.c. 

 pot. bichrorn. 3. After washing for 24 hours in up-graded alcohols to 

 paraffin, material treated in this way was stained with iron-alizarin and 

 crystal-violet, and differentiated with acid as follows : — 1. The sections 

 were placed for 24 hours in a 4 p.c. solution of iron-alum. 2. After 

 washing with distilled water they were transferred to a solution of 

 sulphalizarinate of soda, made by diluting 1 c.cm. of a saturated aqueous 

 solution with 80-100 c.cm. of distilled water. 3. After washing in 

 distilled water the slide or coverslip is placed in a crystal-violet solution; 

 this is warmed until it vaporises, and then allowed to act for 3 to 5 

 minutes longer. The crystal-violet solution is a 3 p.c. alcoholic solution, 

 which is diluted with an equal quantity of anilin water. 4. After 

 differentiating in 30 p.c. acetic acid for 1 to 2 minutes the preparations 

 are washed in running water for 5 to 10 minutes, in order to remove all 



* Beib. Bot. Centralbl., xxiii. (1908) pp. 157-90 (4 pis.). 



t Arch. Mikr. Anat. u. Entwickl., lxxi. (1908) pp. 571-87 (2 pis.). 



