l894-] DUMOND VOLVOX GLOBATOR. 295 



Volvox. Later it appears to be attached to the parent by the adhe- 

 sion of its transparent envelope at the point of contact only, and soon 

 after it is observed to be detached and revolving within the body of 

 the parent. As many as twenty young colonies may be seen in some 

 instances within the body of the parent. Even at this early stage in 

 the life of the young Volvox, there may be seen certain cells wnthin 

 itself, of a larger growth than their fellows, which are destined to 

 become still other colonies. This is the ordinary mode of multiplica- 

 tion in Volvox, and is essentially a process of cell subdivision, taking 

 place during the greater part of the season, and under favorable cir- 

 cumstances is repeated many times, a mature individual developing 

 from an embryo in a few hours. 



The process above described is the common or asexual form of 

 reproduction. Sometimes, however, as Autumn approaches, certain 

 of the cells undergo changes by which they are converted, some into 

 sperm cells, others into germ cells, the greater number, however, 

 remaining sterile. These cells are at first distinguishable only by 

 their larger size. The sperm cells begin to undergo subdivision when 

 they have attained about three times the size of the normal cell. This 

 subdivision is peculiar, in that it is not on the binary plan but the 

 whole mass resolves itself into a number of cells at one and the same 

 time. These secondary cells are seen to consist of an elongated 

 body of an orange or red color, provided with a pair of long cilia. 

 As the sperm cell approaches maturity, the contained cells may be 

 seen in motion. The motion continues with greater violence as they 

 approach the time of their liberation, which is effected by the giving 

 way of the wall of the sperm cell, when the young antherozoids dis- 

 perse to all parts of the cavity of the Volvox sphere. Meanwhile the 

 germ cells continue to increase in size, but do not undergo subdivis- 

 ion, becoming filled with a dark green substance, gradually changing 

 from its original pear-shape to a globular form, projecting 

 into the cavity of the Volvox, and at the same time acquiring a gela- 

 tinous envelope. In this gelatinous envelope the antherozoids literally 

 bury themselves, penetrating to the interior, where they appear to dis- 

 solve, thus becoming incorporated with the contents of the germ cells. 

 Evidently this is a form of conjugation. The product of this fusion 

 is a resting spore, which on the breaking up of the Volvox falls to the 

 bottom of the water, where it remains a longer or a shorter time, 

 and finally develops into a perfect Volvox. Some authorities believe 

 that the resting spores begin to develop on the approach of the fol- 



