MELANENCHYTRAEUS SOLIFUGUS 



Having bleached a specimen by means of a mixture of chlorate of potassium 

 and hydrochloric acid and mounted it in glycerine, I succeeded in making it 

 sufficiently transparent to count the segments exactly, to observe the bundles 

 of chaetae, and to control by examination of the whole animal some results of 

 the study of microtomic series. 



The colour is due to dark pigmentation of the hypodermis (Fig. 7) ; it is 

 so intense that limits of cells or their nuclei are not visible on sections if they 

 are not extremely thin. This fact may depend on the shrinking of the plasm 

 of the epithelium-cells, under the direct action of strong alcohol. In one 

 specimen, unfortunately injured in the genital region, I could recognise the 

 beginning of development of glandular cells in the hypoderm of the twelfth 

 (clitellar) segment (Fig. 8). 



In the cephalic lobe, sagittal sections show a well-marked cephalic pore 

 (Fig. 3 pc) ; in the space between this pore and the mouth the hypoderm is 

 much thickened ; its cells are much elongate, pigmented at their base and 

 apex only. In this region there are in the hypoderm club-shaped bodies, 

 strongly pigmented at their superficial part, nearly pigmentless at their deep 

 or basal part, which shows a large nucleus (Fig. 9 cs). I believe that these 

 bodies are sense cells, possibly organs of sight ; they seem to be connected 

 with a thick nerve, which arises from the lateral commissure of the oesophageal 

 ring, and distributes itself in that region (Fig. 2). A more accurate study 

 of these supposed sense bodies was not possible on preserved material. 



The cutaneous pigment was not confined to the hypoderm ; large cells 

 filled with dark-brown pigment were found around the bundles of chaetae 

 (Figs. 12, 13, 15) and in their neighbourhood. I was not able to recognise the 

 precise nature of these cells ; each of them has a clear round spot showing 

 the nucleus. Brown pigment lies also in the end of the nephridial ducts, 

 near their external opening (Figs. 12, 13). 



The chaetae are slightly sigmoid, more markedly bent at their apical 

 end (Fig. 10). They are about a third longer in the posterior half of the 

 body than in the anterior segments, as it appears by comparing Figs. 12 

 and 13. Each bundle consists of four nearly equal chaetae. The ventral 

 bundle is absent in the 12th (clitellar) segment, which receives the opening 

 of the sperm-duct. 



The brain, as I have made out by graphical construction from a series 

 of sections (Fig. 2), is of nearly quadrate shape, with the anterior margin 

 slightly concave. From the base of each of the lateral commissurae arises 

 the large nerve mentioned above, which distributes to the skin of the 

 cephalic lobe. 



In the mouth-of^^mn^ the epithelium is for a short tract pigmented 

 (Fig. 3). Further backward the epithelial cells are pigmentless ; but in 

 their interstices we find branched cells, filled with granular brown pigment. 

 In the pharynx, the epithelial cells are very high and hardened at their 

 superficial end, but without a distinct cuticle ; between them lie pigmented 

 cells with long branches (Fig. 6). 



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