236 LETTERS TO DR. RITZEMA BOS [CHAP. xxi. 



are such great numbers of Geophilus (centipedes), that there 

 must, I think, be something amiss whether these live chiefly 

 on vegetable matter or on small animal vermin. 



Some inquiry about H. radicicola has been sent to me 

 from Glen St. Mary, Florida, U.S.A., but no new information. 



On Saturday, Professor Ainsworth-Davis wrote to ask me 

 to write a preface to his translation of your "Zoologie," 

 and it will gratify me very much indeed to prepare such a 

 one as I hope may please you. Your book will be a very 

 valuable addition to our educational series, and I shall like 

 very much to be permitted thus to appear in colleagueship. 



October 3, 1894. 



This matter of the ? Tylenchus devastatrix in the cortex 

 seems to me most perplexingly curious. I cannot venture 

 to form an opinion ; I have not the knowledge requisite, but 

 looking at these Tylenchi being smaller than T. devastatrix is 

 customarily known to be, and also their occurring in a 

 locality where devastatrix is not known, the idea just floats 

 in my mind whether they may be $ (males) or, alternatively, 

 larval Heterodera schachtii (" Beet-root " eel- worm). 



But perhaps I am almost wrong in taking up your time 

 with a mere idea, as you work on definite proof, and 

 though the shape of those I mentioned to you much 

 resembled your larval H. schachtii, I had not sufficiently 

 high powers to be sure of the species. I have been trying 

 to make out whether there is ever a definitely formed 

 opening for the exit of the contents of the ? (female) 

 schachtii. In examining one specimen I found a circular 

 orifice with what appeared to rne a regularly formed edge 

 not a merely torn one. On putting this in glycerine under 

 a thin cover-glass, and very lightly pressing it, there first 

 came out a number of little eel-worms, without disturbing 

 the condition of the orifice. I was, however, so desirous 

 that my sister should see the interesting sight that I called 

 her, and when I looked again perhaps in a couple of 

 minutes, the regularity was gone ; the outer skin the skin 

 rather of the female was cracking irregularly from the 

 aperture and giving exit to a mixed collection of eggs and 

 wormlets. I have tried to .find another instance but with- 

 out success. Very many thanks to you for also sparing 

 time to explain to me the meaning of the word 

 " schaumerde." J Now I quite understand and am very 



1 " Schaumerde," is a product of the fabrication of sugar, which con- 

 tains the mineral parts, the salts, of the sugar beet. Therefore it is 

 good for manuring this crop. (J. R. B.) 



