24 SEALS OF THE SHETLAND ISLANDS. 



sume, enter his circulation ; and, connected with this, I ob- 

 serve, that I have never seen any appearances of tubercles 

 or glandular disease in seals. Can this hint throw any ad- 

 ditional light on the beneficial agency of sea air in some of 

 those diseases to which the human frame is liable ? Muri- 

 atic and iodic exhalations must generally pervade maritime 

 situations, as even the sense of smell suggests to us ; and to 

 their influence may probably be ascribed not a little of 

 the sanative efficacy of voyages by sea, or residences in its 

 vicinity. 



I have mentioned that the Phoca barbata may, to a cer- 

 tain extent, be considered monogamous ; but if we are to 

 understand by this that one male and one female attach 

 themselves exclusively to each other, I suspect the rule can 

 hardly be considered a very strict one. The most perfect 

 examples of monogamy occur in birds ; in them it seems to 

 be the general law ; in animals, the exception. It is appa- 

 rently necessary in birds for facilitating incubation ; and 

 the union of the sexes is in them, I believe, for life, and not 

 annual, however indisposed we may be to surrender our 

 poetical visions of the vernal gallantries of the groves. The 

 commencement of this attachment, especially in aquatic 

 birds that produce only two young, seems to be literally ab 

 ovo ; a male and female being in such cases always, I may 

 say, reared in the same nest, and, when arrived at the pro- 

 per age, entering into a more tender union. Almost all 

 carnivorous birds are monogamous. Here, combats for the 

 females would frequently be fatal, from the destructive 

 weapons with which Nature has armed them. Most qua- 

 drupeds possess the power of propagation before they have 

 arrived at their full size and strength ; and it is necessary, for 

 the preservation of the races in their proper perfection, that 

 the male parent should be adult ; and this end can be best 



