374 
TTie Lung Parasites of Cattle and Sheep, 
acquiring sexual maturity ; but I was deterred from this step 
bj the consideration of the almost utter hopelessness of getting 
a positive result from this solitary transfer, and also by the 
hope, which I then entertained, of renewing my experiments on 
a much more extended scale. Under the circumstances, it 
occurred to me to imitate in some degree the conditions which 
obtain in nature, without resorting to the crucial experiment. 
Accordingly, I placed the larva in the hollow of an excavated 
glass slide, immersing the worm in human saliva, and raising 
the temperature to about 70° Fahr. At once, and this is a 
point of some significance, the little worm displajed extremely 
lively mov^ements, such indeed as can only be fitly described as 
frantic. I have no hesitation in saying that the young worm 
showed powers of motion, such as would have enabled it (had 
it been in the windpipe of an animal) to pass rapidly down the 
air-passages. So far satisfied, I removed the slide from before 
the fire, and replaced it under the bell-jar of the fern pan. On 
the following day I found it still alive ; but, in consequence of 
the lowered temperature, its movements were very much re- 
stricted. No fresh structural advances were observed. Again, 
on the succeeding day, without altering the environment, I 
renewed my inspection of the slide, and found that the saliva 
had become thicker and of ropy consistence. However, the 
worm was alive, and though at first lying almost motionless, it 
soon became tolerably vigorous when disturbed. Placing a 
thin glass-cover over it, and waiting my opportunity, 1 at 
length succeeded in obtaining an excellent view of its form and 
structure. My observations were now at an . end. An effort to 
transfer the saliva and the worm to a glass tube (which I after- 
wards carried for a short time beneath the armpit) terminated 
unsuccessfully. 
General Conclusions.— The foregoing experiments and ob- 
servations unquestionably prove that certain larval worms 
(believed to have been reared by the introduction of einbryos 
of the calf's lung-worm into the intestine of earth-worms) will, 
when they are set free, if subjected to suitable conditions, 
undergo a series of morphological and structural changes, and be 
attended with ecdysis. In their later stages these changes are 
accompanied by internal metamorphosis and rapid growth, 
being further signalised by a concurrent activity of movement. 
Eventually, the little worms acquire such a degree of organi- 
sation that both the digestive and reproductive organs are 
already well developed, whilst, at the same time, the young 
male worm displays an incompletely formed bursar, which 
bespeaks its strongyloid origin. 
By these data it would appear that the embryos of the hoose 
