Minot.] 192 ~ [March 5, 
view identical with that advanced by Huxley in his paper! on animal 
individuality. Huxley maintained that all the animals or parts 
arising from one egg represent collectively but a single individual. 
Huxley’s idea appears to me extremely valuable, although it seems 
to me that the use of the word individual is unfortunate and that 
cycle is less misleading. Individual is ordinarily used in the same sense 
as “‘ person” is now employed by Haeckel and his followers; I would 
therefore suggest biad as a still more appropriate term to designate 
a separate animal (or vegetable) existence. Thus each Protozoon is 
a unicellular biad, every Coelenterate or Bryozoic zooid, and every 
individual of the higher animals, whether produced organically like 
the Aphides, or the budded Naids or not, is a biad. The point to 
which I wish to call attention is that the number of biads in one 
cycle of cells varies; in Hydroids, Bryozoa, Cestods, Nais, many 
Tunicates, Aphis, etc., there are several; in other, especially the 
higher, animals there is one biad. Growth may be defined as a 
function of the rejuvenescence effected by impregnation: hence to 
measure growth the whole number of cells living at a given time 
must all be taken into account, no matter whether they are so 
arranged as to form one, several, or many biads. The growth of a 
single Hydroid cannot be compared with that of a mammal, but only 
the growth of a whole colony can be compared, otherwise the com- 
parison is not made between phenomena of the same category. 
Incidentally, I will express my opinion that it is incorrect to 
say: — the impulse or stimulus to develop proceeds from the spermat- 
ozoon. ‘That expression was allowable only so long as it was unde- 
cided whether the spermatozoon merely influenced the egg, or also - 
actually united with it. Since we must now probably regard actual 
fusion of the two elements, male and female, as the universal means 
of fecundation, we can no longer assume that the egg is passive and 
the semen an active stimulus. Certainly, because the egg does not 
move and the spermatozoon is active, is no reason at all for saying 
that in the entirely different functions of growth the same relative 
passiveness and activity exist. Probably neither one nor the other 
sexual product can properly be called the stimulus, but it must rather 
be said, the impulse to divide arises from the fusion of the sperma- 
tozoon with the egg. The moment of fusion, then, is the moment 
when growth of the new cycle begins. 
1 Edinb. New Phil. Journ., L111 (1852), 172. 
