6lO GRIFFIN. [Vol. XV. 



very short. From this it would seem that the longer axis of 

 the prophase cross corresponds to that of the equatorial arms 

 of the metaphase figure and hence the following division is 

 an equation or longitudinal division. 



As previously mentioned, the arms of the metaphase crosses 

 vary extraordinarily in length, and may be of any size from a 

 short knob to a long process. The variation, however, con- 

 forms to an obvious law, since the longer the lateral arms, the 

 shorter the polar, and vice versa, as in Lilitini (Farmer and 

 Moore, '95). Moreover, those spindles containing the greatest 

 number of crosses, with short lateral arms and short-bodied 7"s, 

 are the more advanced. The meaning of all this is very obvi- 

 ous ; the lateral loops are gradually unfolding, and their siib- 

 siancc passing into the polar arms. Throughout this process 

 the central furrow, separating the halves of the polar arms, is 

 sometimes clearly apparent, and sometimes not. The process 

 continuing, the lateral arms steadily decrease in size, and with 

 their disappearance the chromosomes round out to more or less 

 of a ring, in which the central furrow is sometimes most clearly 

 shown (PL XXXI, Figs. 13, 14). The chromosomes now divide 

 in the equatorial plane. 



Upon separation, the halves or daughter- F'j may become 

 immediately contracted, and their bases squared off, or for 

 some time may remain elongate and more or less drawn out. 

 The split separating their limbs is sometimes very clear 

 (PI. XXXI, Fig. 15). During divergence they progressively 

 shorten and contract into sausage-shaped rods, and at or even 

 before telophase they break apart at the angle, and the limbs 

 becoming entirely free, give rise to double chromosome of two 

 short sausage-shaped rods lying side by side (PI. XXXI, Fig. 

 16). However varied the prophase, or even the metaphase 

 figures may be, the daughter-halves behave precisely alike in 

 all cases examined, invariably dividing transversely at the apex 

 of the V. 



We are now in a position to understand certain, at first sight, 

 aberrant chromosomes occasionally met with in the equatorial 

 plate. Observed but once or twice in metaphase, is the doubly 

 curved or elongate 5-shaped rod (II, w), with a slight central 



