Larval Stage of Hj[)Oc!erma bovi.s. 71 



transparent; the older subcutaneous larvae (third stage) are 

 dull white and marked with darker transverse bands; later 

 on they become noticeably thicker and pyriform ; the colour 

 changes to more of a greyish yellow, and subsequently to 

 dark brown ; these larvse have become incapsulated, have 

 perforated the integument, and produce the well-known 

 warbles in the skin. 



In the months referred to one frequently finds that the 

 spinal larva; have crawled out of the tat and are lying in the 

 spaces between the vertebrae ; occasionally they are found 

 with one extremity in the intervertebral spaces. 



On the 28th of last February [1896] 1 also made an inter- 

 esting discovery ; in a yearling beast with a large number of 

 JHi/^jodei-ma-lavvad beneath the skin— the subcutis on the back 

 and loins was violently inflamed and suppurating — three 

 spinal larvae were discovered in addition. On examining the 

 very oedematous oesophagus, I found thirteen (EstncS'hivvsd 

 in the connective tissue between the mucosa and the muscu- 

 laris ; in size, shape, and colour they were similar to the 

 larvai lying in the spinal canal. 



Jn the same way on two occasions after this I also met 

 with CEstrusAarysQ in the wall of the oesophagus. CEstrus- 

 larv£e have likewise been found in the oesophageal wall by 

 Curtice ; it aiterwards appeared that these were the larvas of 

 Hi/podenna lineatum^ which occurs in the United States. 



The interesting statement is also made by Ilorne that 

 in the case of a young bullock he found the whole carcase so 

 full of Hi/poderrnaAia-yse that it had to be withdrawn from 

 consumption. 



Are these spinal and oesophageal larva really those of 

 Hypodenna boin's in the first stage? 



The great agreement between the youngest subcutaneous 

 and the largest spinal larvae in the same animal, the appear- 

 ance of \av\se, under the skin, coupled with the disappearance 

 of the larvae from the spinal canal, is a strong argument in 

 favour of the view that this is the case. It is remarkable 

 that no single investigator has met with the larvae on the 

 way from the vertebral canal to the subcutis. Home asserts 

 that he has more than once noticed in the flesh dirty green 

 larva-tracks, which led from the spinal canal through between 

 the muscles to beneath the skin. In one instance, where 

 both subcutaneous and spinal larvae were present, a larva was 

 met with between the spinous processes of the vertebral 

 column ; hitherto I have not seen definite larva-passages. 

 It is true that when (E's^-ws-larvae are present the epidural 

 fat has a dirty yellow colour; sometimes there is found 



