1893.] Organism without Characteristics of Mother. 225 
them developing normally) that formed dwarf-larve. These 
were in some cases only one-fourth as large as the normal larve, 
but otherwise agreed perfectly with these, and even lived for 
the same length of time, i. e., about seven days. 
This result is in itself certainly full of interest. It shows 
that the sperm-nucleus itself possesses all of the properties 
necessary to function as the first segmentation nucleus, and 
the result, which shows the prevailing opinion concerning the 
nature of fertilization to be erroneous, gives an important sup- 
port to my view, published in several places, concerning the 
interpretation of the process. I desist from considering the 
point further here, in order to turn to the interpretation of the 
experiments dealing with the questions raised concerning 
inheritance. 
With the possibility of fertilizing enucleated egg-pieces and 
of bringing these to a normal dévelopment, we have fulfilled 
all of the conditions in order to reach the end which Rauber 
failed to attain. We have an enucleated egg—for the frag- 
ment has the value of an entire egg, and we are able by means 
of a process of fertilization to introduce another nucleus into 
the egg, the egg still possessing the power to develop. And 
now instead of using a spermatozoon of the same species, we 
introduce the spermatozoon of another in order to produce the 
hypothetical case of “the toad’s egg and the frog’s nucleus.” 
It is even possible to bastardise the egg fragments (obtained 
by shaking) of one species of sea-urchin with the sperm of 
another species, and to rear them far enough to determine 
whether the developing organism shows the qualities of both 
species or only of the one species. Forsuch an experiment the 
sea-urehin presents favorable conditions. It is possible, 
although the results are somewhat variable, to cross-fertilize 
two species standing quite far apart. And in the second place 
the larva of the sea-urchin shows in a very few days, prin- 
cipally through the development of the calcareous skeleton, a 
very well defined shape. This is constant for each species and 
so well defined for each species, that at the age of four days 
we can distinguish the two species of larve just as easily and 
surely as in the adult condition. 
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