THE EXPLOSION OF THE SPERMATOZOA OF THE 

 CRAB LOPHOPANOPEUS BELL US (STIMPSON) 



RATHBUN. 



NATHAN FASTEN, 



DEPARTMENT OF ZOOLOGY, OREGON AGRICULTURAL COLLEGE, CORVALLIS. OREGON. 



(FORTY-SIX FIGURES.) 



CONTENTS. 



Introduction 288 



Material and Methods 288 



Normal Appearance of Spermatozoa 290 



Effects of Chemical Agents on Spermatozoa 290 



Discussion 295 



Summary 296 



Bibliography 297 



Description of Plates 298 



INTRODUCTION. 



For a number of years the writer has been studying the male 

 germ cells of the Decapoda with two purposes in mind: (i) to 

 discover the means by which the mature, dormant spermatozoa 

 of the Decapoda become activated, in order to shed light on the 

 problem of fertilization in this order of Crustacea, and (2) to 

 trace more clearly the process of spermatogenesis. The present 

 paper on the explosion of the spermatozoa of the black-clawed 

 crab, Lophopanopeus bellus, is a contribution involving the former 

 of these problems. 



MATERIAL AND METHODS. 



The material for this study consisted of the living spermatozoa 

 of Lophopanopeus bellus, common in certain localities around the 

 Puget Sound Biological Station, Friday Harbor, Wash. The 

 spermatozoa of this crab are very favorable for study in that they 

 are not enclosed by the numerous spermatophores so common in 

 other brachyura. As pointed out in another paper (Fasten, 

 1917), "in Lophopanopeus bellus it doesn't seem as if numerous 

 spermatophores are developed. Here it appears that one large 

 spermatophore is formed in which the spermatozoa are tightly 

 packed." Since this is the condition all that was necessary to 



