On nucleolar structures of the hypodermal cells of the larva of Carpocapsa. 389 



formly, than that of the ordinary hypodermal cells, appearing finely 

 granular. Each nucleus is large, rich in deeply staining chromatin; 

 the largest nuclei are excessively amoeboid (Fig. 6), with the amoeboid 

 processes projecting toward the cuticular spine. 



In each of these nuclei is a single, large, spherical chromatin 

 nucleolus , often vacuolated , which stains like the chromatin but 

 more densely. It is probable that it has had a similar mode of for- 

 mation to that found in the nuclei of the feet; but this point could 

 not be determined, since no transitional stage could be found between 

 the spine-producing cells and the undifferentiated hypodermal cells. 



4. Oiant free Cells of the Body Cavity. 



In the haemolymph are found enormous free cells, by far the 

 largest of the whole body (Fig. II C). They show no structural 

 resemblance to the minute blood cells, but a marked similarity to the 

 largest of the hypodermal spine-producing cells. They resemble the 

 latter particularly in regard to the nucleus (Fig. 10; compare with 

 Fig. 6), which is large, very amoeboid, the chromatin of deep staining 

 intensity, and with a large chromatin nucleolus. A number of small, 

 true nucleoli are also present. The nuclear membrane is of excessive 

 tenuity around the amoeboid processes ; and the latter are either 

 blunt and lobose, or in the form of thin sheets. The cell body is 

 not amoeboid, more or less rounded in outline, and possesses a cell 

 membrane but no cuticular ditfereutiations ; it is proportionately much 

 larger than that of the spine-producing cells. The cytoplasm appears 

 finely granular throughout. 



At first I concluded that these free cells were derivatives of the 

 spine-producing cells ; that is, cells which after producing the cuticular 

 spines of the hypodermis had become loosened from the hypodermis, 

 displaced into the body cavity, and there had increased in size. This 

 view was based mainly on the similarity of the nuclear structure of 

 the two. But Prof. William M. Wheeler, with whom I discussed 

 the subject, considered this assumption probably erroneous: he con- 

 sidered them to be oinocytes^), that is, large blood cells of hypo- 

 dermal origin arising segmentally in the vicinity of the tracheal stig- 

 mata, such as he had found and described for the main groups of 

 pterygote Insects ^). 



1) Compare Wielowiejski, Ueber das Blutgewebe der Insecten, in: 

 Z. wiss. ZooL, V. 43, 1886, p. 512. 



2) Wheeler, Concerning the "blood-tissue" of the Insecta, in: 

 Psyche, 1892; here a complete literature review. 



