231 PROFESSOR E. RAY LANKESTER. 



pigment is completely dissolved away from them so as to 

 leave them colourless. They have not the nature of " cells 

 within cells," for they possess nothing within them compar- 

 able to a cell-nucleus. Rather they have been compared 

 each to a nucleus. They are devoid of special wall or 

 capsule, and have been observed in a state of transverse 

 division, from which it is inferred that they may multiply by 

 fusion, just as nuclei may multiply in multinuclear cells. As 

 to the internal structure of the colourless basis of a vegetable 

 chlorophyll-corpuscle, there appears to be less known than 

 might be anticipated. The central portion appears to be 

 the seat of the formation of starch in certain cases, and this 

 implies a differentiation of superficial and central substance. 

 The green pigment is sometimes observed to impregnate 

 only the superficial layer of the corpuscle so as to form a 

 kind of green-coloured shell enclosing colourless contents 

 (starch, &e.). This is important for the comparison with 

 the supposed chlorophyll-corpuscles of animal tissues. 



The development of the chlorophyll bodies of plants and 

 the effect upon them of physical agents is at present receiv- 

 ing renewed attention. It has been observed that they are 

 preceded by colourless corpuscles which under the influence 

 of sunlight develop the green pigment in themselves. 

 And it has also been observed that in certain saprophytes 

 allied to green plants, but themselves devoid of green pig- 

 ment, colourless corpuscles are present which appear to 

 represent the chlorophyll bodies, and these acquire a green 

 colour when acted upon by chemical agents (sulphuric 

 acid). 



If we find green-coloured corpuscles present in the cells 

 of an organism which exhibit the form and structure just 

 detailed, we have evidence so far in favour of such corpus- 

 cles being of a nature identical with that of the chlorophyll 

 bodies of plants. 



This line of evidence in relation to tlie inquiry into the 

 supposed existence of chlorophyll in animals we may add 

 as a sixth to those already enumerated, calling it the mor- 

 2ihological eindence. 



It may be added here that over and above the broad phy- 

 siological and morphological characters of the chlorophyll 

 bodies of green plants which have been above cited, there 

 are other morphological and ])hysiological cliaracters less 

 important or less fannliar, which may of course be made use 

 of in a comparison between these bodies and similar bodies 

 occurring in animals. 



Definite proof of the occiirrence of chloropliyll in an 



