MALE ORGANS FOR SPERM-TRANSFER IN THE 
CRAY-FISH, CAMBARUS AFFINIS: THEIR 
STRUCTURE AND USE 
E. A. ANDREWS 
From the Zoélogical Laboratory, Johns Hopkins University 
THIRTY-ONE TEXT FIGURES AND FOUR PLATES 
INTRODUCTION 
The present paper is a contribution to our knowledge of the 
means that lead to the fertilization of the egg. It is part of the 
history of the sperm outside the body of the animal. 
Sexual reproduction in most complex animals involves the trans- 
fer of the sperm from one animal to another, before the eggs can 
be fertilized. 
Among animals the various methods by which the sperm is 
transferred may be grouped under the three heads, diffuse, direct, 
indirect. By diffuse sperm transfer we mean the discharge of the 
sperm into the water, where it may meet the eggs outside of the 
female, as in certain coelenterates, echinoderms and annelids, 
or may be drawn into the body of the female, as in certain lamel- 
libranchs. By direct sperm transfer we mean the method found 
in the majority of complex animals, in which there is more or less 
direct application of the terminal parts of the passages leading 
the sperm to the exterior to the passages leading from the exter- 
ior direct to the eggs. In this group there is commonly a true 
copulation. 
By indirect sperm transfer we mean those peculiar complex 
methods of getting the sperm from the testis to the eggs that are 
found in a few cases amongst the great groups of animals, as in 
JOURNAL OF MORPHULOGY, VOL. 22, No. 2 
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