AND ON THE DIRECT AGENCY OF THE SPERMATOZOON. 
249 
April 2, 1851 . Atmosphere 55°. — Ten eggs were passed into a large glass cell, and 
each egg was touched onee only with the pin point dipped lightly into the fluid for each 
egg. This experiment was perfectly successful, as the chamber was formed above 
the yelk in four or five of these eggs, and at the end of five days three of them had 
produced embryos. In these instances the pin had been allowed to remain in contact 
with the egg, and the fluid to drain off" it for one or two seconds. 
Sia: eggs were also placed in another cell and each was touched with the loaded 
pin point when the fluid employed had been obtained about a quarter of an hour. 
Two of these eggs became partially fecundated, as shown in the formation of the 
respiratory chamber. In eaeh of these the yelk became slightly elongated, a symptom 
which always precedes the first cleavage ; yet they did not undergo further alteration, 
but with the remaining four were abortive. 
Twenty-three eggs were included in a large cell as a further experiment, and each 
egg was touched once with the pin-point loaded each time, when the fluid employed 
had been one hour and three quarters mixed with water. Four of these also had the 
chamber formed, and segmentation commenced in them, at the end of four hours 
and a half; but the majority were only partially feeundated, as only one of the 
twenty-three eggs produced an emhryo. The fact of this production, however, shows, 
that an exceedingly small amount of influence, even at a long period after the fecun- 
datory fluid has been removed from the body in which it is generated, is sometimes 
sufficient to occasion the development of an animated being; and that although a 
plurality of spermatozoa, supplied to the egg, appears always to be necessary to 
ensure fecundation, yet that the result seems to depend less upon the abolute given 
number, or numerical relation of these bodies, to the egg, than on the measure of 
vitality possessed by those which are brought into actual encounter with it, as a very 
small number appears to be more efficient when employed immediately after their 
removal from the body, than a much larger number after a prolonged interval. 
{h.) Pin-head application of fluid. — The preceding experiments having been made 
with the smallest quantity of fluid, and consequently with the fewest spermatozoa 
that could be applied directly to the egg, it was desirable to increase the number of 
these bodies without applying them in excess, and for this purpose the head of a very 
small pin, the smallest size used by insect-collectors, was employed, instead of the 
point of a larger sized pin. An endeavour was also made, as in the previous trials, 
to ascertain the number of spermatozoa which the head of this sized pin, dipped 
lightly into fluid, was likely to be the means of conveying to the egg. It was then 
found that the loaded pin-head deposited on a plate of glass, in the minute quantity 
of fluid which adhered to it, from at least fifty to one hundred and fifty spermatozoa ; 
a number which was not only fully sufficient to fecundate each egg to which the pin- 
head was applied, but also other eggs which might happen to come into contact with 
these in the same cell and water in which the experiment was made. 
Six eggs, placed in a single cell, were each touched once only with the pin-head. 
