When a tomographic image is displayed, the operator of an ultrasonic diagnostic apparatus is allowed to know the timing to optimize the image quality and decide by him- or herself whether optimization needs to be done now or not. The force required to form the caulked portion is reduced, and the caulked portion is less susceptible to damage. The architecture employed by one or more embodiments of the invention comprise at least one dispatcher, at least one processing unit, at least one program memory, at least one program address generator, at least one data memory. The rear part includes a second connection portion, a connection plate extending from a top end of the second connection portion, and two chain stays and two seat stays extending from the connection plate. The invention also includes a display rack, comprising means, e. The method can treat a great quantity of larvae simultaneously, achieve batch infection of larvae or pupae, save manpower and effectively infect larvae or pupae at a high infection rate.