lyg NATURAL SCIENCE. March. 



condition the convolutions of the beaded thread have again distributed 

 themselves over each divided nucleus, and soon enlargement and 

 total separation take place, as in Fig. i8. 



In the divided organism containing this organism the division- 

 line soon again appears in the nucleus, and successive fissions go on. 

 But in the nuclei belonging to the condition of special fissipartition 

 shown in Fig. 7, the nuclei present quite a distinct appearance. No 

 wall is at all discernible in connection with it, and it is slightly larger 

 than the ordinary form ; it is highly refractive, and, on critical exami- 

 nation, does not show the exquisitely fine convoluted beaded thread 

 of the usual nucleus, but dissociated white, and slightly darker, some- 

 Avliat oblong granulations, as shown in Fig. 19- When in the usual 

 order, in the act of fusion shown in Fig. 9, L, this nucleus comes into 

 contact with the ordinary one (7, 6), there is almost immediate 

 " melting of either into other," the whole mass resulting being milky 

 and almost opaque, taking a white star-like appearance, resulting 

 apparently from the diffusion of the whole mass through the entire 

 plasm of the fused organisms, for in the course of a short time it 

 disappears, and, as in Fig. 1 1 , N, a non-nuclear triangular body results. 

 The bodies ultimately emitted from this are of extreme minute- 

 ness, and partially opaque ; and in their growth one of the most 

 remarkable features appear. 



In Fig. 21, if ^ represent the original spores as sent out into the 

 fluid, ^ will represent their growth in form and relative size in an 

 houri i shows one of the same in an hour-and-a-half, while; (Fig. 22) 

 gives the result of growth at the end of nearly three hours ; but now 

 very Httle advance in size is made ; there is a pause, as if the form 

 had been arrested in growth by death. But, on critical examination, 

 there is found to be a very slight enlargement taking place, and with 

 it the formation of the inteynal beaded thread-hke convolution which 

 may take thirty to fifty -minutes to complete, as in Fig. 22, K. 



From this time growth is rapid ; but it appears to proceed from 

 within the nucleus outward, as shown in Fig. 23, where a smaU part 

 of the body-substance has arisen outside the nucleus, n, and, at this 

 stage, the two flagella are seen as though emerging from the nucleus, 

 as at /, m. The body-substance now rapidly grows until the adult 

 form and size are reached, as in Fig i, A, when the processes of the 

 life-history once more repeat themselves. 



It would thus appear that every point in the cyclic changes in 

 tlais organism originate in, or are initiated by, the nucleus. Fission 

 is not only indicated, but begins first in the nucleus, while the nuclear 

 changes during fission are worthy of careful note. The change in 

 the character of the nucleus in certain forms after fission is full of 

 suggestion, and that their subsequent union with nuclei of the 

 common type is equivalent to fertilisation, we can scarcely doubt. 

 Not less interesting is the origin of the nucleus in the growing form, 

 and its relation to the growth of the body. 



