s6 - observations c>x filari.e. 



Letter by Dr. Manson. 



" Amoy, 20th June, 1879. 

 " T. Spencer Cobbokl, Esq., F.R S. 



" Dear Sir, — Last mail brought me your kind letter of 28tb 

 April, and enclosures. I am glad your ncAv work is about coming 

 out, and hope my London agents have forwarded a copy long ere 

 this time. Had I been in possession of it, I would not have 

 troubled you with questions about Distoma crassum. I suspect you 

 are very often annoyed in this way, and I am very much obliged for 

 your courtesy in noticing my letter. 



" I will forward by this mail filaria-impregnated mosquitos. 

 They are preserved in glycerine, and were fed on the blood of the 

 man whose case I ajDpend. His scrotum I sent to you some time 

 ago in charge of Dr. Holmes, a surgeon in one of Holt's steamers, 

 who kindly promised to hand it to you. 1 hope you will pardon the 

 delay in sending the mosquitos ; being in general practice here, the 

 many interruptions this entails make work of this sort exceedingly 

 difficult to carry out quickly. 



" I read in the Lancet lately an account of the discussion on a 

 Lymph scrotum sent from India, and felt disappointed that the 

 Filarice were not found. I determined to send you the first scrotum 

 I amputated, and in which I had unquestionable evidence of Filarice. 

 The scrotum 1 send is the result, and to complete the case 1 send 

 particulars of the man's history, and the result of the examination 

 of his blood before and after the operation. The case is one of 

 much interest, as it exhibits, first, the transition from Lymph 

 scrotum to Elephantiasis ; secondly, it demonstrates unmistakably 

 that the parent worm is not necessarily present in the affected 

 tissues themselves, though probably in close proximity. I had 

 hoped you might find the Filaria Bancrofti in the scrotum, but the 

 embryos persisting in the blood weeks after the operation show that 

 this is unlikely. Thirdly, it illustrates well a new fact in the 

 history of the Filaria — the young escape into the circulation at 

 regular intervals of twenty-four hours, the discharge commencing 

 soon after sunset and continuing till near midnight, from which time 

 till the following noon their numbers gradually decrease ; by two or 

 four o'clock till six they are nearly completely absent. This is a 

 striking and most suggestive fact, and in connection witli it one 

 might be tempted to speculate on the causes of the periodicity of 



