807 
Experiments on Fundulus. 
Turning to Fundulus we get much more satisfactory results. The 
egg readily lends itself to experiments of all kinds. It is easily kept 
and has a great amount of vitality and these qualities taken in con- 
nection with its large size make it most favorable for experimental 
studies. 
Removal of Blastomeres. 
It is possible to remove from the egg one of the first two blasto- 
meres without interference with the development of the remaining 
hemisphere. With a sharp needle the membrane can be pierced above 
the blastoderm and the needle point thrust into one of the two blasto- 
meres without injuring the yolk beneath. When the needle is removed 
a part of the protoplasm spurts out of the hole. By gently com- 
pressing the membrane above the injured blastomere one can often 
remove the remainder of the blastomere so that it lies entirely with- 
out the egg membrane. The remaining uninjured blastomere at first 
flattened on one side soon rounds up until it is circular in outline 
and continues to segment. In some cases only a portion of the proto- 
plasm is removed in the operation and the remaining portion of the 
injured blastomere may either continue to divide (if it contains the 
nucleus) or is subsequently overgrown and obliterated by the perfect 
half or its products. In the present account we may exclude such _ 
cases from our description and speak only of those where total remo- 
val of one blastomere has taken place. Attempts were also made to 
pierce one of the two cells with a hot needle but in all such cases 
either the protoplasm extruded on removing the needle or else the 
heat killed both blastomeres. Exact records of sixty-eight cases were 
obtained and in these the early stages of segmentation were foll- 
owed and embryos reared. About twenty of this number died how- 
ever before the embryo appeared. If we take as an example an 
egg in which the first two blastomeres are equal in size and remove 
one of the two cells we would find that the remaining blastomere 
rounds up, that then a resting stage comes on, and usually the oper- 
ated egg will fall behind the normal egg in the rapidity of its divi- 
sions. The blastomere divides into two equal parts applied to one 
another, and is in all respects a miniature copy of the normal two- 
cell-stage. The furrow always appears in the plane where the second 
furrow of the normal egg would lie. A second furrow follows the first 
at right angles to it and a four-cell stage result again like the normal 
stage of correspondent segments except in point of size. The third 
furrows comes in more or less at right angles to the last but a number 
