286 



4) Dr. Ben ham is surprised that I should congratulate Clapa- 

 rède for having worked out the vascular supply of the clitellum. 



I did so because Horst and other writers had doubted the accu- 

 racy of Claparède's account. 



5) Dr. Benha m states: — »Mr. Cole [gives] a theory of his own 

 as to the passage of the spermatozoa from one worm to another : a 

 theory founded on no firm basis of fact but on »probabilities«. 



I really do not know what this means. I have no theory on this 

 subject. My remarks were merely a criticism of other theories. May 

 I suggest that Dr. Benham be good enough to read my paper? (If 

 Dr. Benham has got mixed up again, and is speaking of the formation 

 of the cocoon, my actual words are: — »I can add nothing to the 

 little already known«; »my idea is«; »what we must expect to find«.) 



6) Di. Benham refers to my »explanation« of the tubercula pu- 

 bertatis. 



My actual words are: — »Both these conjectures [i. e. conjectures 

 respecting the function of the tubercula] are improbable, and the tu- 

 bercula pubertatis must for the present remain a puzzle.« 



I think these quotations show that what Dr. Benham was care- 

 ful enough to label »A criticism« might very fitly have been included 

 among the »Personal-Notizen«. 



Edinburgh, May 22nd 1894. 



2. Preliminary Note on the Eye of the Leech. 



By Harriet Bell Merrill, Instructor in Biology, Milwaukee High School. 



eingeg. 30. Mai 1894. 



In a recent paper (Beiträge zur Kentnis des Hirudineen- Auges, 

 in: Zool. Jahrbücher, Bd. 5. Abth. f. Morph, p. 552. 1892), Dr. B. L. 

 Maier, a pupil of Prof. Bütschli, calls attention to an interesting 

 feature in the innervation of the Hirudinian eye. He finds that the 

 nerve going to the eye divides at the base of that organ into two bran- 

 ches, the larger perforating the pigment cup and passing as an axial 

 cylinder through the center of the eye, giving off branches to the 

 visual cells as it passes. The other smaller branch passes outside the 

 pigment cup on the incomplete side, and innervates the clear cells 

 lying above and crowding beyond the pigment layer. 



Prof. Whitman, in a paper published in the Journal of Morpho- 

 logy in 1889 , states that in the eye of Clepsine there are two kinds of 

 cells, the clear cells and what he calls the »tactile cells«, which 

 he considers homologous with the tactile cell« of the serial sense or- 

 gans. These two kinds of cells are innervated by two branches of the 



