14 



The degrees of numerousness, used for estimating, are the fol- 

 lowing (arranged according to the increasing number): 



I = chlorophyll corpuscles absent in the preparation. 



II = „ „ very rare „ „ „ ; viz. 1—4, 



III = „ „ rare „ „ „; in some fields 1. 



IV = „ „ rather rare „ „ „ . 



V = „ „ here and there „ „ „ . 



VI =: some chlorophyll corpuscles present in the preparation. 



VII = several „ „ ' „ „ „ „ ; in every field 



VIII = somewhat more „ „ „ „ „ „• [+3. 



IX = rather numerous,, „ ,, „ „ „. 



X = numerous „ „ „ „ „ „ . 



XI = very numerous „ „ „ „ ,, „ . 



XII = a mass of „ „ „ „ „ „ ; the fields fill- 



ed up with them. 



It goes without saying, that the limits between these different 

 degrees may not be considered as having been strictly indicated. 



In the same way were examined for many sponges: the num- 

 ber of oildrops — present in a preparation or in an amoebocyte 

 — , the number of globules of carbohydrate (coloured by I) — 

 present in an amoebocyte — , and the number of amoebocytes — 

 present in a preparation — ; here too the same degrees were used. 



One should, however, not try to compare these numbers 

 (I — XII) mutually in the different groups (that of the chlorophyll 

 corpuscles, of the oildrops, of the globules of carbohydrate, and 

 that of the amoebocytes) too exactly. — Besides, there will never be 

 any reason to do so. — So, for instance, one should not consider 

 a number of chlorophyll corpuscles in a preparation, indicated 

 by X, as being exactly the same as a number of amoebocytes 

 also indicated by X. These degrees of numerousness may only 

 be directly compared within each group; while for the groups 

 mutually this only counts in a very limited way. This is inevi- 

 table, when using the method of estimating the number: for 

 our estimation is involuntarily influenced by the extent of the 

 corpuscles the number of which must be estimated, and by* the 



