PENDROSOMA KADIANS, EHKEXBEKG. 
163 
formed, and it may be tliat the size was not as great as it 
would be when the outline was completed. There is no reason 
to believe, however, that there is any considerable growth in 
the gemmula after the first faint Hues marking out its contour 
ai’e noticeable. 
The average of the shorter diameters of sixteen gemmulaj 
was about 35’5 /x and the average of the longer diameters 
about 41 ju. We may i-oughly express, therefore, the diffe- 
rence in size between the two kinds of gemmulae as a difference 
of 29'6 p by 29 6 n in Lernaeophrya and 35'5 /x by 41 ^ in 
Dendrosoma. There is not much difference in size, probably, 
between the lai-gest gemmulae of Lernmophrya and the 
smallest gemmulae of Dendrosoma, and there is clearly con- 
siderable variation in the size of the gemmula3 of both 
genera. 
But still it may be considered a fact of some systematic 
value that the gemmulm of Dendrosoma are larger than those 
of Leriueoph ry a. AVe found, unfortunately, no Tricho- 
phrya forms showing formed gemmulm, and we can therefore 
give no near details of them. They have been described by 
Biitschli, Sand, and others, but we have not found any 
measurements given of them in the literature of the genus. 
The gemmulae of Dendrosoma are usually found in well- 
developed individuals, and are frequently situated at the 
base of the arms (text-fig. A), but they also occur in the 
course of the arms and moi’e rarely in the stolons. 
'Pile gemmulae at the base of the arms is a very character- 
istic feature of the specimens from the Bridgewater canal. In 
the specimens from Birmingham the gemmula3 are more 
frequently found some little distance above the base. 
In the earliest stage of gemmule formation there is a slight 
swelling in the arm, and two or three curved lines (fig. 19, o.) 
appear in the cytoplasm and mark the external boundary 
of the future • gemmula. A narrow crescentic space often 
appears between these lines aud the cytoplasm. The mega- 
nucleus sends off a short branch which ends in a knob-like 
swelling towards the concavity of these lines (fig. 20). The 
