SPERMATOGENESIS OF CANCER MAGISTER. 279 



spermatid transformations, and steps in the opening of the sper- 

 matozoa. With the exception of Figs. 1-15 and Figs. 67-69, all 

 the drawings in the accompanying plates are from smear prepara- 

 tions. Figs. 1-15 are from sections, while Figs. 67-69 are from 

 living spermatozoa as viewed in the crab's body fluids. 



The material for sectioning was cut into small pieces and fixed 

 with numerous fluids. The best fixatives, however, were found 

 to be Flemming's strong and the Meves-Duesberg modified 

 Flemming. The sections were cut 5^1 in thickness and then 

 stained by either the iron-alum haematoxylin method with a 

 counterstain of acid-fuchsin or by the safranin, gentian-violet 

 method. 



The living spermatozoa were studied under the oil-immersion 

 lenses in various fluids, such as the body fluids of the crab, sea 

 water, in iso tonic and hypotonic solutions of various salts (NaCl, 

 KC1, CaClo, NaNO 3 and KNO 3 ), and in distilled water. By 

 fixing the spermatozoa on the slide with either osmic acid fumes 

 or Bouin's fluid, these structures could then be stained in iron- 

 hsematoxylin and acid-fuchsin and all the stages in their explosion 

 could subsequently be studied. 



3. DESCRIPTION OF TESTIS. 



The testis of Cancer magister has already been described else- 

 where (Fasten, '15). It is a bilobed organ lying in the cephalo- 

 thoracic region, below the cardiac chamber and above the diges- 

 tive glands. Each lobe is profusely tubular and runs laterally 

 along the stomach. During June and July these testicular lobes 

 are prominently developed and fill up a large part of the upper 

 cavity of the cephalothorax. Below the anterior portion of the 

 heart the two lobes of the testis unite, and from this junction 

 point two stoutly convoluted tubes, the vasa deferentia, originate 

 and run posteriorly to the base of the fifth pair of walking legs 

 where they open to the outside. 



During the latter part of June and the early part of July the 

 tubules in the outer and middle regions of each testicular lobe 

 are usually undergoing rapid proliferation. Some of them are 

 filled with spermatogonia, while others contain growth stages 

 and still others show primary and secondary spermatocyte 



