324 American Quarterly Microscopical Journal. 



we have to deal with such soft tissues as young embryos, and more par- 

 ticularly the blastoderms, we require a material of a different character. 

 It appears that a clear solution of pure collodion is especially suited to 

 such cases, when employed according to the plan here proposed. After 

 trying successively mixtures of wax and oil, soap and oil, soap, gelatin, 

 and various other media, the author attempted to use collodion. What 

 appeared most objectionable in the use of many of the above mixtures was ; 

 first, the want of transparency, not permitting the operator to direct the knife 

 to the desired point ; and next the necessity of removing the mixture from 

 the section before mounting, which required so much washing as to 

 endanger its perfection. The tenacity and transparency of collodion 

 brings it to our attention, but at the same time, its contractility and 

 hardness, when dry, only indicate its possible use with resistant and 

 relatively hard objects ; it has thus been employed by Dr. Latteux already. 

 For very delicate tissues, like the blastoderms of embryos, it would not be 

 possible to employ it in this condition. 



If a drop of collodion be allowed to fall into a quantity of alcohol at 

 36"^, it forms in this liquid a sphere which does not alter in volume, and 

 presents the elasticity and consistence of a piece of caoutchouc, and, at 

 the same time, retains its perfect transparency. The ether diffuses into 

 the alcohol and evaporates, while the solid collodion imbibes the alcohol 

 and does not lose it again by dessication. The method of using this 

 material for imbedding soft tissues is as follows : After hardening in 

 osmic acid and alcohol, or in any other way, and staining with carmine, 

 they are placed in alcohol. From this they are transferred to ether for a few 

 moments, and then to a pure collodion solution, in which they may remain 

 from ten minutes to twenty-four hours, according to the extent to which 

 it is desired to have the collodion penetrate the tissues. They are then 

 placed in alcohol. The collodion solidifies without contraction and all the 

 parts of the tissues are retained in their normal position. Thus prepared 

 the tissues may be cut into sections at once, or preserved indefinitely in 

 the alcoho'. The sections may be mounted at once in glycerin, without 

 removing the collodion, as its presence is not to be observed. This 



medium has other advantages, which we cannot enumerate here. 



Note on the Constitution of the Spermatozoids of the Bull- 

 Frog, by F. Henneguy. Terrestrial Diatoms, by Julian Deby. — 



A memoir read before the Societe Beige de Microscopie, in January, 



1879. Fossil Calcareous Alce. From Xature, March 27th, 



1879. New Laboratory Microscope, by Dr. J. Pelletan. — An 



instrument designed by the writer, fully described. 



VZEITSCHRIFT FUR MIKROSKOPIE (Xo. /, /ci>(;).— Con- 

 tributions to the Anatomy of the Eve, by Dr. Ludwig Lowe. — 

 This lecture is illustrated by two large sectional cuts, one of the human 

 eye and the other of an eye from the embryo of a dog, which afford 

 an excellent idea of the structure of this oroan and the relation of 



