384 F. W. GAMBLE AND FREDERICK KEEBLE. 



fi-om direct observation guided by a knowledge of tlie form 

 and appearance of the colourless elements that are found in 

 normal Convoluta at a later stage, and also from experi- 

 ments given below. That leucoplasts are absent is a deduction 

 from our experiments made with filtered and sterilised water, 

 which showed that the development of cells with leucoplasts 

 or chloroplasts is not a constant feature of the early life of 

 Convoluta, however bright the light maybe; whereas, if 

 leucoplasts were present in the egg and followed a course of 

 development such as occurs in plants, their division and 

 metamorphosis into chloroplasts would, in Convoluta as in 

 plants, be a constant phenomenon in light cultures. We show 

 that it is possible to maintain Convoluta for weeks after 

 hatching, and to expose it for the greater part of each day 

 to direct sunlight, without any indication of chloroplasts 

 arising with them. The development of green cells in certain 

 cultures, their inconstancy in others, and their absence from 

 still other experimental animals, prove that thei-e is no 

 constant development of green cells in Convoluta from 

 leucoplasts. We conclude that up to the time of hatching 

 Convoluta is devoid of any trace of its future assimilating 

 tissue. 



There is no habitual infection of Convoluta by a green 

 cell. The green cell develops from a colourless cell. We 

 have seen two such translucent cells the day after hatching, 

 but the time of their appearance varies very greatly. They 

 lie in the central syncytium or gut, surrounded by one or 

 more nucleated wandering cells, and it is probable that from 

 whatever source they were derived fresh supplies may accrue. 



We have observed the transformation of colourless into 

 green cells two days after hatching, a result obtained by 

 subjecting the larval Convoluta to several hours' direct 

 sunlight. If diffused light is employed, the change of colour 

 occupies a much greater length of time (from one to two 

 weeks). Once the change is effected, multiplication of the 

 green cells proceeds apace. The change of colour is accom- 

 })aiiied by a change of site. The colourless cells occur in 



