Ria 
s eeation repeating the form of the original paren e" 
‘Yet bgunouen seemingly so mysterious, is er this a of de- 
se. Alternation of Generations in Radiata. 
tions have been made on ~~ subject by Professor Agassiz. 'The 
alternations are as follow 
. The Medusa ciate eggs ;— 
2. The eggs, after passing through an infusorial state, fix 
‘themselves am become polyps, like Coryne, Tubularie, or Cam- 
* panulariee ;— 
3..' The, ia produce a kind of bud that finally drops off 
and: becomes a Med 
‘Thus the’ egg of 4 a Me -dusa, in such cases, does not produce 
a Medusa, Bae after going through the intermediate state of a Ms 
‘Or if we commence duith the polyp, the series is thus :— 
“1. The polyp produces bulbs that become Meduse ; 
2. The Meduse produce eggs; 
3. ‘The eggs produce 
This i is what.is called by Steenstrup  slegsintion of Geter 
= tions ;’ ’ and he considers the earlier generation as preparing the 
: he for the latter. ‘It certainly seems to be a most mysterious 
ssa. parent ‘producing eggs which afford a progeny, of 
a Wholly different form,. (even so different; that. rete have 
_ arranged the progeny.in another grand division of the R La dia ee 
velo opme mon in the vegetable kingdom ?, Is it not the 
prevalen "process in. ae en of « our + gardens | and fields, with 
which we 
| well ki : howh is us, that in tost Genie, our trees an 
shrubs for example,gr rowth from the’ seed brings out a bud “ 
leaves ; from this bud after. elongation, other teaf-buds are often 
developed, each consisting like the first of a number of leaves. 
It is an admitted fact (as ony be found i in T reatises on? ial 
ra copra: To some cases the plant forms but a single leaf-bud ; 
in others, where there is successive gemmation for a period, the 
number is gradually multipled, and more or less according to the 
habit of the species. So among polyps, there is the simple and 
compound Tubularia, Campanularia, and the like. 
After the plant has sufficiently matured by the production and 
growth of its number of leaf-buds, there is a new development— 
a flower-bud y—consisting of the .~ ee as the leaf- bud, 
but ge unlike it in general ap nece—as much so, as th 
usa is unlike the polyp. The Rower-indvetiei starts as a 
) from the leaf-individual, or the group of leaf-individuals, 
s in every respect to the bulbs from the ee 
