2 Pub. Puget Sound Biol. Sta. Vol. 2, No. 32 



availability of the animals, which should furnish an abundance of easily 

 accessible material, particularly favorable for some lines of experimental 

 research. 



It has been the past experience that Leptasterias enters its repro- 

 ductive season in the latter part of February or first of March. At the 

 end of the first week of April, 1912, many of the young had completed 

 their metamorphosis and were escaping from their mothers, while the 

 youngest stages then available had approximately half finished their meta- 

 morphosis. It seems likely that the entire season extends over a period 

 of 6 to 8 weeks, but the exact period of development of the individual can- 

 not yet be given. 



As is to be expected in an animal possessing the brooding habit, the 

 number of young produced by a single female is relatively small, while 

 the eggs are very large and heavily laden with yolk, which suffices to 

 carry the development through the metamorphosis. The largest number 

 of young taken from a single female was 1160, but young females in their 

 first season have only a few dozen. The eggs are large, from 0.6 to 

 1.1 mm., varying with the size of the female producfng them. They are 

 brightly orange-colored. The eggs are extruded from ventrally located 

 gonopores. On account of their gelatinous envelope, they adhere in a 

 mass which the female gathers into the oral region of her pursed-up body 

 and holds securely with her tube-feet (Fig. 2). The eggs adhere so 

 strongly to each other in the early stages that it is nearly impossible to 

 isolate them in the living condition without injury. The fertilized egg 

 has a distinct membrane surrounding it within which the egg floats freely 

 (Fig. 3). In the early stages of brooding the female doubtlessly secures 

 no food, but in later stages small gastropods are to be found in her mouth. 

 These are sometimes entirely hidden by young starfish. Under these 

 conditions the young starfish are usually in their last stages of meta- 

 morphosis or even fully developed, their distinctly white color betraying 

 the exhaustion of their yolk supply. At this stage the young have pro- 

 trusible stomachs and it does not seem impossible that they may thus share 

 in the mother's food. 



The cleavage stages were not obtained, but there is no reason for 

 believing the segmentation in Leptasterias essentially different from that 

 described for Asterina, Cribrella or Solaster. Neither is it possible to 

 describe the formation of the blastula or gastrula. The form of the larva 

 is first betrayed in a spherical embryo in which there is no superficially 

 visible sign of blastopore. This embryo cannot be superficially distin- 

 guished from an egg, since it is still enclosed by the membrane. At one 

 pole of this splierical embryo the 3 "arms" of the preoral lobe appear. 

 They are at first very much depressed and only faintly visible (Fig. 4). 



