V 



159 



Time will not permit me to give yon an account of the history of the 

 •development of the strongyles of cattle and sheep, but I may remind you 

 that already, in 1880, I had the pleasure to explain to the Clab what was 

 then known in this respect, and gave a detailed notice of some original 

 experiments. On the occasion in question the value of the discussion was 

 greatly enhanced by the observations which fell from Mr. Beulah. 



The differential diagnosis of the various species of Strong ylus is, taken 

 by itself, a matter of great interest, zoologically speaking.* As a refine- 

 ment in this department of observation, I may mention that it is perfectly 

 possible for an expert in this branch of helminthology to detect the differ- 

 ences subsisting between the various embryos alike of strongyles and other 

 allied nematoids. 



In conclusion, let me add that it must be obvious to the meanest 

 capacity that if we would stamp out divers parasitic plagues that affect 

 both man and beast we must endeavour to ascertain whence each species 

 comes and whither it goes. 



Alas ! the labour of such researches is practically endless. What a task 

 the problem presents for generations of microscopists yet unborn ! Of the 

 hundreds of known species of helminths only a few have been exhaustively 

 studied, so to say. 



The number of the species thoroughly studied may be counted on the 

 ends of our fingers. We have Trichina spiralis, Fasoiola hepatica, so 

 beautifully worked out by Thomas, and a few Tamia, Echinorlujnchi, and 

 one Pentastuma, concerning whose several life histories tolerably complete 

 records exist. 



In this regard, the collection of species and their zoological determination 

 is one thing. Anatomical observation, aided by sections, staining, and 

 mounting, is another step gained. But then there remains the question of 

 experiments on living animals, involving both expense and much personal 

 sacrifice of time. Both of these difficulties might eventually be bridged over, 

 were we not met with obstacles arising from the determined hostility of 

 certain well meaning people who disapprove of this, the most essential part 

 of the biological method of research. We can make no solid advances in 

 helminthology unaided by experimental research, which method, after all, 

 however freely employed, would serve to allay far more suffering than it 

 could produce. 



Unfortunately, the influence of some of these obstructors of science is 

 very considerable; so great, indeed, that one might almost speak of it as 

 being equalled only by the profundity of ignorance which characterises its 

 foremost abettors. A few simple lessons gathered from a contemplation of 

 the behaviour of parasites would do some of these obstructors and senti- 

 mentalists a great deal of good ; and I venture to think that our dear and 

 grand old Shakespeare would, as regards the vexed question, have ranged 



* At this point Dr. Cobbold gave a brief account of the diagnostic marks presented 

 by the tails of strongyles. Drawings representing on a large scale the hoods of the 

 male worms were referred to; especial attention being called to those of Strongylus 

 micrulus and Str. filaria of the ca!f and sheep respectively, The ray-patterrs of the 

 hoods of S. paradoxus and S. dentatus of the pig, of S.filicollis and S. contortus of lambs, 

 of Str. clathratus of the elephant and S. commutatus of the hare were also described and 

 contrasted.— Ed. 



