Neoplasms 385 



ceived the name of congenital moles. The explanation of their oc- 

 currence is based upon the development of the eye-lids. In early 

 fetal life the tissue covering the outer surface of the eye-ball which 

 ultimately becomes the conjunctiva is directly continuous with the 

 skin. Cutaneous folds arise and approach each other from the mar- 

 gin of the orbit to ultimately become the eye-lids, and their surfaces, 

 which are continuous with the covering of the eye-ball, become con- 

 verted into conjunctival mucous membrane. This conversion (into 

 mucous membrane) is dependent upon the complete occlusion of the 

 covering of the eye-ball, and if a portion or even all of the latter 

 remains uncovered, it persists as skin (Sutton). 



Dermoid Cysts occur in the Ovaries. They may be composed 

 of skin or mucous membrane together with the appendages peculiar 

 to these structures such as hair and sebaceous glands, and contain a 

 mucoid fluid. Mueller quotes Esser as authority for their occurrence 

 in the dog. Dermoid Cysts containing rudimentary molar teeth 

 also occur in the Temporal Region (Werwey, Cadiot & Almy). 

 They usually undergo regressive metamorphosis, the cells consti- 

 tuting the lining of the cyst becoming detached to form part of the 

 cystic contents. Inflammation of the interior follows entrance of 

 pyogenic microorganisms, and the matter gains exit by fistulous tract 

 in or near the auricular region. 



Parasitic Fetuses are composed of cells of parts of individuals 

 parasitic upon another individual. They are not common. A very 

 interesting case was witnessed by Hodgkins where the parasite had 

 two fully developed feet and was attached to the umbilicus of a 

 normal puppy. 



(4) Cysts 



A cyst is a tumor containing one or more cavities filled with 

 fluid or semi-fluid contents resulting from abnormal dilation of 

 pre-existing tubules or cavities. Strictly speaking, a cyst is not a 

 neoplasm, the whole style of a cyst being totally distinct from the 

 tumor proper, and so many widely differing factors may lead to cyst 

 formation that it is better to treat them as a totally distinct section. 

 Nevertheless, the purpose of the work will perhaps be best served by 

 including them in the same chapter. 



Closely following Sutton's classification, we recognize in 

 the dog: 

 26 



