238 MISS A. L. EMBLETON ON THE ANATOMY 



from Plate 11. figs. 6, 7, 8, is of a very remarkable form. It was difficult to decide in 

 certain cases Avhether this neck was or was not equally connected witii both masses ; 

 if so, it certainly soon becomes the exclusive property of the mass that will become 

 the egg. There is a considerable difference in the two masses, more especially as regards 

 the contents. The future egg-mass is almost oblong in shape, while the other portion is 

 spherical and smaller ; the granules in the former are larger and more concentrated than 

 in the latter. It is a fact of interest and of some significance that the two masses or 

 jmrts of the egg always respond in strikingly diffex'ent ways to various staining reagents ; 

 for instance, when treated witli methyl green in acetic acid and mounted in dilute 

 glycerine, the true egg-mass and isthmus show a clear green-blue colour, while the other 

 mass is purple. I observed that this stain behaved with similar distinction in other cells 

 belonging to different parts of the body, the nuclei presenting the same colour as the 

 egg-mass, and the cytoplasm of the cells the same as the yolk-mass. I could find no 

 nucleus in the egg. 



In the earliest stages the egg is an oval body containing coarse granules ; this stage is 

 followed by one in which a slight constriction is observable in the middle; this gets 

 more and more marked until the condition of two masses connected by a fine isthmu.s is 

 assumed. All these stages are found within a membranous covering (PI. 11. figs. 2-5). 

 In the latest stages a curious structure is present on the neck part of this dumbbell- 

 shaped egg; it is a valve-like j)i'OJection, pointing towards the yolk-body like a lip. 

 There is still a connection between the two masses (PI. 11. figs. 6-9), but where this lip 

 is situated there is an appearance of tine papillation or stiialion on the wall of the tube. 

 At the distal end of the yolk-mass there is evidence of some thickening of the wall, but 

 I cannot find any definite structural peculiarity beyond this. This dumbbell-shaped 

 condition measures "35 mm. 



I also examined flies which I bad kept alive for a week or two on flowering plants, 

 and in them I found eggs as stalked bodies ; that is, the yolk-mass had disappeared, and 

 lelt only the true egg-mass with the isthmus appearing as a stalk. This appendage ends 

 as a curious forked apparatus, rej)resenting the valve or lip present on the connecting 

 tube in an earlier stage. The papillated appearance is now more conspicuous ; in the 

 neck of the stalk, at the point where it forks, there is a plug of protoj)lasmic matter 

 (PL 11. fig. 7). Prom this stage, though I could not observe the act of ovij)Osition, I 

 traced the egg to its destination in the body of the scale, where it is always situated 

 on the right side of the anus (if one looks at it dorsally, towards the bead). The form 

 of the egg now is identical with that when last seen in the fly; it measures "25 mm., 

 and always has the plug of matter in the stalk. In older Coccids, where the young 

 larva is present, then the tail of the larva is seen to be capjied with the remains of the 

 stalked egg-case, the body of the vgg having split into two when the larva emerged. 

 This stalk measures -05 mm. 



To summarize the processes I have described, I may say that the mass of matter from 

 Avhich an egg is developed becomes constricted in the middle until it finally assumes a 

 dumbbell form ; /. e., two masses are connected by an isthmus. In this condition, 

 changes between the two masses take place by means of the isthmus, as the result of 



