1909. ] GONADIAL GROOVES OF A MEDUSA. is 
out of the large number taken only one here and there was 
at the exact stage when the sex-cells were being extruded ; 
and, further, it appears that the whole of any particular gonad-loop 
is not rive at one and the same time, so that only a portion of it 
may be shed at a time and so perhaps be found in the gonadial 
groove. 
After taking these facts into consideration, it is gratifying to 
have been able to find some specimens in which the grooves 
showed unmistakable indications of the presence of sex-cells. 
In one or two cases the small masses of material were with- 
drawn from the grooves by means of a fine pipette and then 
examined under the microscope. By this means both eggs and 
masses of spermatozoa were recognised. However, it was not 
possible to figure these structures accurately under these 
conditions ; and although it was proof that the grooves actually 
serve as gonoducts, yet it was deemed necessary to obtain figures 
of the sex-cells in the groove. For this purpose, the remainder of 
the specimens which showed grooves with contents were dissected 
and the necessary portions were removed entire. These latter 
were stained in bulk in borax-carmine for forty-eight hours, 
dehydrated, and embedded in paraffin-wax. Sections were cut at 
right angles to the interradial axes along which the grooves lie. 
In the preparation of the material for sectionizing, there was a 
large amount of contraction owing to the great thickness of the 
mesogloal tissue, and for this reason the lining epithelium in 
many places became broken up and displaced from its original 
position. In spite of this, however, the grooves have retained 
their position and proportions fairly well, and it has been possible 
to obtain figures of the sex-cells in sitv. 
The first figure (Pl. XXIV. fig. 1) shows a gonadial groove the 
lining epithelium of which (e) has been fragmented somewhat. 
A mass of nucleated tissue is shown lying within the limits of 
the groove. On the examination of this with high power 
objectives (fig. 2) it was seen to consist of spermatozoa. Along 
with the latter there are other large cells which are in 
various stages of disintegration and are apparently the nurse 
or nutrient cells (Aders*). The spermatozoa in the middle 
of the figure can be easily made out, each having a deeply stained 
nuclear head. In the case of a few spermatozoa, the clear, 
almost globulax middle-piece can be distinguished. Flagella are 
also very numerous in the section. From the densely aggre- 
gated nature of the two masses of male cells at the top and bottom 
of the figure, and also from their relations with the nutrient 
cells, it would seem as though spermatogenesis, or at least some 
of the final stages of the process, may take place within the limits 
of the groove. 
Fig. 3 shows a mass of eggs lying in a groove. Unfortunately, 
the piece of material from which this section was cut turned 
* Zeits. f. wiss. Zool. Ixxiv. 1903. p. 95. 
