130 H. CHARLTON BASTIAN ON THE STRUCTURE AND 
that during the whole period of the growth of the female*, till the maturity of its young, 
it does not cause any inconvenience, and but rarely attracts attention; and this has in 
consequence been termed by Mr. Busk the “ latent period " of its existence. 
Or it may be that females only penetrate the integuments, impelled, as is frequently 
the case with the females of other animals, by a sort of instinct to seek a new habitat for 
the produetion of their young. But if, as we have supposed, the young worms penetrate 
before the genital organs are completely formed, this latter explanation would be rather 
improbable, as the sexual instincts could not then be reasonably supposed to come into 
operation. 
But however this may be, whether both males and females penetrate, or females only, 
I think there can be little doubt that this occurrence (at all events as far as warm- 
blooded animals are concerned) must be regarded as an exceptional rather than 
an invariable event in the history and development of these microscopic worms, 
when we consider the vast number in which these creatures, low in the scale of organiza- 
tion, are found in situations favourable to their existencey. So that these worms may 
be eonsidered to have an ordinary existence in the waters and damp places which they 
naturally frequent, having then their sexual organs fully developed and capable of pro- 
ducing true ova in the usual manner, as well as an exceptional or extraordinary existence 
as parasites of certain warm-blooded creatures, in which condition females only have 
been met with, that seem to have the outlets of their sexual organs undeveloped, and to 
contain young which have been formed from internal buds or pseudova by a process of 
zooid development. 
Whether or not the young so produced are capable of existing externally, in their 
natural medium, there does not seem at present sufficient evidence to enable us to 
decide. But there are no real grounds for the belief, on the other hand, that the disease 
is contagious, as it has been sometimes stated to be. "There is, indeed, no evidence to show 
that the young can or do continue their existence beneath the integuments, where they 
have been reared, although they are frequently liberated in this situation by the rupture 
of the parent worm. In these cases the young die and are discharged with the pus and 
other inflammatory products which are the invariable sequence of such an accident. 
We now come to the consideration of the last question to which I shall allude, viz. as 
to whether there be one species of Dracunculus only in the various countries in which the 
Guineaworm is endemic, or several different species corresponding to one or more genera 
of worms. This-question was mooted long ago by Dr. M‘Clellandt, but does not seem to 
have received much attention since. He says, “It appears to us probable, however, that 
we have many kinds of Dracunculus even in India; should this be the case, some may 
* This must be very rapid: it has been calculated by Mr. Busk that the rate of increase is frequently about an 
inch per week. 
T Of course it is highly probable that these aquatic worms may inhabit ponds and places wholly unfrequented by 
Aa = rarely so by quadrupeds; so that it does not seem at all likely that more than the smallest fraction of their 
Peu voee would ever have an opportunity of becoming parasites, if such a state were a necessary stage in 
t Calcutta Journ. of Nat. History, vol. i., 1841. 
