91 



In some lesions examined many larvae have shown marked 

 degeneration with a well-developed necrosis of the surrounding 

 tissues, while other forms have been well preserved, and have 

 caused little or no necrosis of the tissues. This suggests that, 

 in some cases, the larvae have made their appearance in the 

 tissues not by one massive invasion, but by smaller invasions 

 repeated over a certain period of time. For the most part, 

 however, all larvae in a given lesion appear to be in approxim- 

 ately the same state of preservation or disintegration. All 

 the larvae seen in the different lesions examined have appar- 

 ently been dead, but the retrogressive processes vary markedly 

 in extent in different tumours. 



In the older lesions it is not possible to determine the 

 exact nature of the material contained in the circular or 

 ovoid spaces in the necrotic areas, but in the light of the 

 knowledge gained from examining earlier lesions, there can 

 be no doubt that the material is the debris of a larval 

 Nematode. 



It must be insisted here that in the older lesions one may 

 be unable to detect any degenerated larvae, or even the 

 spaces which they at one time occupied. This fact renders it 

 important that the histopathological picture in all its vari- 

 ations should be thoroughly studied and understood. If this 

 is done a diagnosis can usually be made, in spite of the fact 

 that no casual organism can be demonstrated. 



The foregoing descriptions of the microscopic appearances 

 apply equally to tumours from the penis and from the sheath, 

 except that in the latter situation the tissue reaction is far 

 more marked and the necrotic areas more diffusely scattered 

 throughout the tumour. In both situations there may be 

 marked endothelial proliferation in the intima of the 

 arterioles. This is often seen in the deeper parts of the 

 tumour. Sometimes there is thrombosis of the vessels. The 

 necrotic areas, however, are in no way associated with the 

 vascular changes, but are apparently due entirely to decom- 

 position products originating in the degenerating larva. 



The microscopic appearances of the lesion from the meta- 

 carpus vary somewhat from those described above. The 

 tumour consists throughout of dense fibrous tissue, in which 

 areas of embryonic connective tissue cells with an infiltration 

 of mononuclear leucocytes appear as islands. These areas are 

 usually somewhat circumscribed, and in some of them are 

 found degenerated larvae with slight surrounding tissue 

 necrosis and the formation of multinucleated cells. There is 

 a diffuse infiltration of all the tissues with eosinophile 

 leucocytes. There is little formation of new tissue apart from 



