1909] Eitter: Halocynthia johnsoni a - i 



so absorbed in questions of how the germ can be so constituted 

 as tn make inheritance go as it does in these cases, thai attention 

 is diverted from the actual observations in which the questions 

 are rooted. But this neither adds to aor subtracts from the Eacts 

 themselves, either objective or subjective. There is a well worn 

 maxim about not being able to "see the woods because the trees 

 are so thick-." The converse of this might be a useful maxim. 

 It happens not infrequently that one becomes so intent upon the 

 grandeur of a forest as to ignore the individual trees of which 

 it is composed. The artist may legitimately do this. The scient- 

 ist cannot. Mendelists need not of course spend all their time 

 cogitating over the circumstance that dominance and recessive- 

 aess resl essentially on the observation that some of the offspring 

 resembli one parent more than the other. They are. though, 

 almost certain to go astray if they ever really ignore the fact. 



My purpose in this inquiry is to see something of the outcome 

 of attention to the trees as well as to the forest of merism. A 

 goodly number of bald facts and some of the "law and order" 

 as one species of ascidian exemplify them we have already seen. 

 Now we may push inquiry concerning the still wider bearings of 

 these somewhat further. Before doing so we must look at the 

 mode of multiplication of stigmata a little more closely. For this 

 we turn again to Damas's work. Referring to the three modes 

 of stigmata formation recognized by his predecessors, he writes : 

 "One sees that these three modes of multiplication of stigmata 

 are only variations of the same process which may be charac- 

 terized as follows : 



1st. The stigmata are subdivided by triangular languets 

 which cut the stigmata perpendicular to their long axes. 



2nd. The essential (characteristique) epithelium of the newly 

 formed stigmata seems to be produced always from the epithelium 

 of the pre-existing stigmata." 



"A consequence of these facts is that typically all the epithe- 

 lium bordering the definitive stigmata is derived from the epi- 

 thelium of the six protostigmata" (p. 23). The group of epi- 

 thelial cells in the stigmatje border which in many ascidians gives 

 rise by division to the epithelium of the new stigmata is specially 

 definitively set off in Ciona intestinalis (see Damas's figs. 7 and 8. 



