No. 473] 



EGG-LAYING OF CRAYFISH 



355 



like those inside the cement glands. It may be that the secreted 



glaire passes from the latter state into the former. 



The glaire itself resembles tlie stalks in l)eing a clear matrix 



full of droplets that elonoate when the o-laire is stretclied but while 



some of the droplets nrv 1 li", oihvv> arc as hiri^v a> .'17' X 



112 /X and many are cnnipouiuf nnnl.ive (h'.-p. of 12 to l':. n. 



Glaire and egg-stalk are thus not ideutical thou<j:h the stalk might 



well arise from glaire matrix. 



Without, then, imagining any special action of the hairs we 

 may suppose that the eggs become fastened to them because they 

 are smeared with the densest secreted matter from the pleopod 

 glands. AH the surfaces having been made scrupulously clean 

 the secretion can spread over the hairs as they hang like feathers 

 in the water and as the glands along the pleopod are segmentally 

 or interruptedly arranged, the hairs may well be stuck together 

 in sniail (lusters or brushes of denser glaire separated by, more 

 watery nlairc. When the eggs roll down along these brushes 



stick to one another ;dl along\he 'side of the pleopo.l. Once 

 stuck and more or less buried in the glaire on the hairs the pull 

 of their weight will drag otit enough glaire to make a stalk. That 

 more eggs stick to the hairs than to the body of the pleoj)od may 

 be largely a matter of relative area. 



Some eggs that were loose in the abdominal chamber when tlie 

 rest had stalks, some hours after being laid, ])resente(l the follow- 

 ing peculiar appearance upon one side. A rounded area agreeing 

 with the size of the bell of a stalk was thickly <cf with minute drops 

 on the outside of the outer egg-case while fine threads inside this 

 case suggested that some filose, or else secretional activity of the 

 egg might have been going on over this area through j)ores in the 

 egg-case. As was known to Chantran, each egg has a large ])olar 

 area and it seems possible that s])ecial activities of the protoplasm 

 there may be concerned in localizing the attachment of the egg 



of the stalk. 



