Digest of Current Literature. 75 



seems to be a sort of mania on the part of many naturalists to propose 

 specific names on the least provocation. 



Spongilla fluviatilis is found in very many forms in different lo- 

 calities which, by careful comparison, show such gradual gradations 

 that they are undoubtedly merely varieties of one species. A plate 

 showing the forms of spicules is given. 



JOURNAL DE MICROGRAPHIE. 



This Journal, edited by Dr. J. Pelletan of Paris, although only in its 

 second year, is undoubtedly one of the most valuable journals published 

 in the special line of microscopy. In plan it is quite different from any 

 other, and the " Review " with which each number opens, from the pen 

 of the editor, is always full of interest. 



We briefly abstract from the numbers at hand as follows : 



May, 1878. 



Lymphatic Hearts. — Prof. Ranvier. — A continuation of a lecture 

 at the College of France. It begins in this number with a study of the 

 nerve of the posterior hearts, and then follow a few words on the 

 lymphatic hearts of serpents. 



The last division here given relates to the structure of these organs 

 in Batrachians. 



Observations on the termination of the motor nerves in 



THE striated MUSCLES OF THE TORPEDO AND THE RaVS, AND ON 

 THE RESEMBLANCE BETWEEN THE ELECTRIC AND MOTOR PLATE OF 



THE Torpedo.— Prof. C. V. Ciaccio. — Continuation. 



New Researches on the intimate Structure of the Retina 

 IN Birds.— Dr. Al. Tafani.— Continued. 



Study upon Foreign Microscopes. — Dr. Pelletan. — This is one 

 of a series of articles on the subject. A full and good description of 

 Mr, Zentmayer's " Centennial " stand is given. Dr. Pelletan is not 

 sparing in his praise of this specimen of American workmanship. 



Following this is quite as long an account of Mr. R. B. ToUes's new 

 large stand, which also receives a due portion of praise. 



The Vernier applied to the Body-tube of the Microscope. 

 — L. M. Bawens. — The author states that about ten years ago he 

 applied a vernier to his microscope (Jackson model), for the purpose 

 of measuring the thickness of cover glasses and other work. 



June, 1878. 



Lymphatic Hearts. — Prof. Ranvier.— Continued. 



Observations on the Termination of the Motor Nerves, 

 ETC. — Prof. C. V. Ciaccio.— Continued. 



The Microscopes at the Paris Exposition. — Dr. Pelletan. — 

 This is the first of a series of articles, and is a general view of the 

 microscopes of the whole exhibition. 



