117 
Protomyxa is proved by these experiments. This pheno- 
menon, remarkable in itself, is of the greatest interest 
both for the doctrine of individuality (Tectology) gene- 
rally, and for the natural history of the Protozoa spe- 
cially. It has recently lost much of its marvel, that divisi- 
bility by artificial separation is in all probability a very 
general quality of the lower organisms ( i . e., the Protozoa), 
since it appears in much higher organized as well as in more 
strongly differentiated animals and plants. 
I will take this opportunity of observing that during my 
stay at Lanzarote, I made many experiments on the artificial 
division of the Hydro-medusae, which were followed by the 
most surprising results. The extraordinary divisibility and 
powers of reproduction in the common fresh-water hydra 
have been universally known since Trembley’s time,, and 
have also been established in the marine Hydrozoa by Dal- 
yell’s experiments. On the other hand, the possibility of 
artificially dividing the medusae themselves (Gymnoph- 
thalmata) , was previously unknown. My experiments 
proved that it prevails to an amazing extent in many 
medusae, especially in those belonging to the family Thau- 
mantiadce of Gegenbaur (Laodicei of Agassiz). In several 
species of this family I could divide the umbrella into 
more than a hundred pieces ; and from each piece, pro- 
vided it only contained a portion of the margin of the 
umbrella, grew in a few days (from two to four) a complete 
small medusa. Merely a loosened shred of the fringe 
on which the base, the adjoining piece of the edge of 
the umbrella, remained, formed a medusa in a few days. 
The result that I obtained with other hydro-medusae was 
still more surprising. Here I could divide the globular 
non-differentiated cell-mass (or the ciliated globular larva) 
which had come out of the egg-furrows into several pieces, and 
from each piece was developed a complete larva. As I shall 
detail these experiments in division in another place, they 
are only casually mentioned here. 
As soon as I had perceived the complete nature of the orange- 
red star-shaped specks on the Spirula shell as Rhizopod-like 
Protozoa, the idea naturally forced itself upon me that the 
neighbouring previously described red balls were torpid 
or encysted individuals of the same species ; and that those 
balls in which the contracted orange-red contents were di- 
vided into numerous small balls were connected with 
monogenetic reproduction. 
The red balls which I carefully detached from the Spirula 
shell, and placed in shallow watch-glasses filled with sea 
