440 PHILOSOPHICAL TRANSACTIONS. [aNNO 1788. 



oviduct ; and one of them appeared as if it had parted with a yolk the preceding 

 day. The ovarium still exhibited a cluster of enlarged eggs ; but the most for- 

 ward of them was scarcely larger than a mustard seed. 



I would not be understood to advance that every egg which swells in the 

 ovarium, at the approach or commencement of the propagating season, is brought 

 to perfection ; but it appears clearly that a bird, in obedience to the dictates of 

 her own will, or to some hidden cause in the animal economy, can either retard 

 or bring forward her eggs. Besides the example of the common fowl above 

 alluded to, many others occur. If you destroy the nest of a blackbird, a robin, 

 or almost any small bird, in the spring, when she has laid her usual number of 

 eggs, it is well known to every one, who has paid any attention to inquiries of 

 this kind, in how short a space of time she will produce a fresh set. Now had 

 the bird been suffered to have proceeded vi^ithout interruption in her natural 

 course, the eggs would have been hatched, and the young ones brought to a 

 state capable of providing for themselves, before she would have been induced 

 to make another nest, and excited to produce another set of eggs from the 

 ovarium. If the bird had been destroyed at the time she was sitting on her first 

 laying of eggs, dissection would have shown the ovarium containing a great 

 number in an enlarged state, and advancing in the usual progressive order. 

 Hence it plainly appears, that birds can keep back or bring forward, under cer- 

 tain limitations, their eggs at any time during the season appointed for them to 

 lay ; but the cuckoo, not being subject to the common interruptions, goes on 

 laying from the time she begins, till the eve of her departure from this country : 

 for though old cuckoos in general take their leave the first week in July, and I 

 never could see one after the 5th day of that month,* yet I have known an in- 

 stance of an egg's being hatched in the nest of a hedge-sparrow so late as the 

 15th. And a further proof of their continuing to lay till the time of their 

 leaving us may, I think, be fairly deduced from the appearances on dissection of 

 the female cuckoo above mentioned, killed on the 3d of July. 



Among the many peculiarities of the young cuckoo, there is one that shows 

 itself very early. Long before it leaves the nest, it frequently, when irritated, 

 assumes the manner of a bird of prey, looks ferocious, throws itself back, and 

 pecks at any thing presented to it with great vehemence, often at the same time 

 making a chuckling noise like a young hawk. Sometimes, when disturbed in a 

 smaller degree, it makes a kind of hissing noise, accompanied with a heaving 

 motion of the whole body.-^ The growth of the young cuckoo is uncommonly 



* Though I am unacquainted with an instance, yet I conceive it possible, that here and there a 

 straggling cuckoo may be seen afier this time. — Orig. 



f Young animals, being deprived of other modes of defence, are probably endowed with the 

 powers of exciting fear in their common enemies. If you but slightly touch the young hedge-hog. 



