424 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1912. 



generations. In the resulting products of this repeated division, one 

 part was always normal while the other inherited a hornlike pro- 

 cess. There was considerable difference in the form and size of 

 this process, as well as in its position; at times it appeared anteriorly, 

 then in the middle or posteriorly, so that the progeny would obtain 

 this process from the anterior or posterior extremity of the parent. 

 From the nineteenth generation on, the process remained on the 

 anterior end, assuming a peculiar function; the anmial used it as a 

 gliding shoe and moved upon it on the walls and bottom of the 

 container. 



While Jennings produced this horn like process through lack of 

 food, McClendon produced the same by means of a centrifugal or 

 rapid whirling of the Protozoan. In the first followmg fission the 

 daughter cells each possessed a horn. Later, as in Jennings's ex- 

 periments, only one of the daughter cells was provided with a horn, 

 the second one, being normal, gave rise to normal progeny only. 



Another new character, on the other hand, also resulting from 

 insufficient food in cultures, made by Jennings and McClendon, 

 could, in spite of transfer into a rich food medium, be transmitted 

 even by apparently normal examples, namely, the tendency to 

 incomplete fission (fig. 16), in which the daughter individuals remain 

 attached, formmg chains. In this manner long wormlike colonies 

 arise, from which now and then an individual becomes separated; 

 this, however, produces chains again, directly, or these are formed 

 by its progeny. 



Similar fusion was produced by Stole in a worm, Aeolosoma Jiem- 

 pricMi (fig. 2), which multiphes by budding — that is, asexually, by the 

 use of old culture water containing scant nourishment. In this case 

 the phenomena is not transmitted to the progeny, again a reminder 

 that asexual reproduction does not always embrace a complete 

 transmission of all the characters, whether inherited or acquired. 

 This worm normally has a smooth head and six pairs of bundles of 

 setse, on the sides of the body (l-Fl). In the reproduction (fig. 2T), 

 a new head and body with six pairs of bundles of bristles (setae) are 

 budded at the posterior end and later detached. But when subjected 

 to starvation the bud fuses with the main stem into a single individual 

 (fig. 26), which now possesses more bundles (setse) than the normal 

 worm. If this individual be now placed in a fresh food medium and 

 begins to bud there (bT), it will produc;e from the very beginning only 

 individuals with six pairs of bundles of setse. Likewise, the offspring 

 are provided with the normal number of setse, when budded from a 

 parent which, instead of having an increased number of seta? produced 

 by hunger, has a lesser number produced by mechanical separation 

 (fig. 2a). 



